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<section id="vector-data-management-optimization">
<span id="vector-optimization"></span><span id="index-0"></span><h1><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Vector Data Management & Optimization</a><a class="headerlink" href="#vector-data-management-optimization" title="Link to this heading">¶</a></h1>
<dl class="field-list simple">
<dt class="field-odd">Author<span class="colon">:</span></dt>
<dd class="field-odd"><p>Jeff McKenna</p>
</dd>
<dt class="field-even">Contact<span class="colon">:</span></dt>
<dd class="field-even"><p>jmckenna at gatewaygeomatics.com</p>
</dd>
<dt class="field-odd">Original Author<span class="colon">:</span></dt>
<dd class="field-odd"><p>HostGIS</p>
</dd>
<dt class="field-even">Last Updated<span class="colon">:</span></dt>
<dd class="field-even"><p>2026-03-29</p>
</dd>
</dl>
<nav class="contents" id="table-of-contents">
<p class="topic-title">Table of Contents</p>
<ul class="simple">
<li><p><a class="reference internal" href="#vector-data-management-optimization" id="id1">Vector Data Management & Optimization</a></p>
<ul>
<li><p><a class="reference internal" href="#choose-the-right-vector-format-for-your-needs" id="id2">Choose the right vector format for your needs</a></p></li>
<li><p><a class="reference internal" href="#spend-time-to-review-gdal-s-associated-driver-page-for-your-chosen-format" id="id3">Spend time to review GDAL’s associated driver page for your chosen format</a></p></li>
<li><p><a class="reference internal" href="#connect-to-your-data-through-ogr-gdal" id="id4">Connect to your data through OGR/GDAL</a></p></li>
<li><p><a class="reference internal" href="#learn-review-the-various-ogr-utilities-to-manage-your-vectors" id="id5">Learn & Review the various OGR utilities to manage your vectors</a></p></li>
<li><p><a class="reference internal" href="#index-your-data" id="id6">Index your data</a></p>
<ul>
<li><p><a class="reference internal" href="#tileindexing" id="id7">Tileindexing</a></p></li>
<li><p><a class="reference internal" href="#add-a-spatial-index-to-your-data" id="id8">Add a Spatial Index to your data</a></p></li>
<li><p><a class="reference internal" href="#add-an-attribute-index-to-your-data" id="id9">Add an Attribute Index to your data</a></p></li>
</ul>
</li>
<li><p><a class="reference internal" href="#splitting-your-data" id="id10">Splitting your data</a></p></li>
<li><p><a class="reference internal" href="#handling-your-vector-layers-in-the-mapfile" id="id11">Handling your vector LAYERS in the mapfile</a></p></li>
<li><p><a class="reference internal" href="#shapefile-notes" id="id12">Shapefile Notes</a></p></li>
<li><p><a class="reference internal" href="#postgis-notes" id="id13">PostGIS Notes</a></p>
<ul>
<li><p><a class="reference internal" href="#indexing-with-postgis" id="id14">Indexing with PostGIS</a></p></li>
<li><p><a class="reference internal" href="#specifying-a-unique-id-column" id="id15">Specifying a Unique ID column</a></p></li>
<li><p><a class="reference internal" href="#debugging-speed-issues-with-postgis" id="id16">Debugging speed issues with PostGIS</a></p></li>
</ul>
</li>
<li><p><a class="reference internal" href="#databases-in-general-postgis-oracle-spatialite-geopackage-microsoft-sql-server-mysql" id="id17">Databases in General (PostGIS, Oracle, SpatiaLite, GeoPackage, Microsoft SQL Server, MySQL)</a></p>
<ul>
<li><p><a class="reference internal" href="#enable-connection-pooling" id="id18">Enable Connection Pooling</a></p></li>
<li><p><a class="reference internal" href="#set-extent-at-the-layer-level-of-mapfile" id="id19">Set EXTENT at the LAYER level of mapfile</a></p></li>
<li><p><a class="reference internal" href="#verify-that-your-table-has-a-spatial-index" id="id20">Verify that your table has a Spatial Index</a></p></li>
<li><p><a class="reference internal" href="#for-wfs-services-prevent-using-default-full-extent" id="id21">For WFS services, prevent using default/full extent</a></p></li>
</ul>
</li>
</ul>
</li>
</ul>
</nav>
<section id="choose-the-right-vector-format-for-your-needs">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Choose the right vector format for your needs</a><a class="headerlink" href="#choose-the-right-vector-format-for-your-needs" title="Link to this heading">¶</a></h2>
<ul>
<li><p>The best/optimal vector data source for MapServer in terms of speed-of-display
is <a class="reference internal" href="../input/vector/shapefiles.html#shapefiles"><span class="std std-ref">Shapefile</span></a>.</p>
<div class="admonition tip">
<p class="admonition-title">Suggerimento</p>
<p>MapServer 8.0 includes a new <a class="reference internal" href="../utilities/coshp.html#coshp"><span class="std std-ref">coshp</span></a> utility to create
“Cloud Optimized Shapefiles”</p>
</div>
</li>
<li><p>A recent format designed for vector performance, with similar map draw
speed in MapServer as Shapefile, is <a class="reference internal" href="../input/vector/flatgeobuf.html#flatgeobuf"><span class="std std-ref">FlatGeobuf</span></a>, and is
recommended for cloud performance.</p></li>
<li><p>For databases, MapServer displays <a class="reference internal" href="../input/vector/postgis.html#input-postgis"><span class="std std-ref">PostGIS</span></a>
layers very fast, and some custom tricks are included in the MapServer source
specifically for PostGIS + MapServer draw speed. PostGIS is therefore recommended.</p></li>
<li><p><a class="reference internal" href="../input/vector/sqlite.html#sqlite"><span class="std std-ref">SpatiaLite</span></a> is recommended
for those who require a portable format, and works very well with MapServer.</p></li>
<li><p><a class="reference internal" href="../input/vector/geopackage.html#geopackage"><span class="std std-ref">GeoPackage</span></a> («GPKG») is also very popular for portability,
and works very well with MapServer.</p></li>
</ul>
<p>Here are some rudimentary map draw speed results, with the
MapServer 8.0 release code (running on Windows with <a class="reference external" href="https://ms4w.com">MS4W</a>):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">FlatGeobuf</span> <span class="p">(</span><span class="n">native</span><span class="p">)</span> <span class="mf">0.008</span><span class="n">s</span>
<span class="n">Shapefile</span> <span class="p">(</span><span class="n">native</span><span class="p">)</span> <span class="mf">0.010</span><span class="n">s</span>
<span class="n">FlatGeobuf</span> <span class="p">(</span><span class="n">OGR</span><span class="p">)</span> <span class="mf">0.013</span><span class="n">s</span>
<span class="n">Shapefile</span> <span class="p">(</span><span class="n">OGR</span><span class="p">)</span> <span class="mf">0.023</span><span class="n">s</span>
<span class="n">GeoPackage</span> <span class="p">(</span><span class="n">OGR</span><span class="p">)</span> <span class="mf">0.042</span><span class="n">s</span>
<span class="n">SpatiaLite</span> <span class="p">(</span><span class="n">OGR</span><span class="p">)</span> <span class="mf">0.045</span><span class="n">s</span>
<span class="n">PostGIS</span> <span class="p">(</span><span class="n">native</span><span class="p">)</span> <span class="mf">0.053</span><span class="n">s</span>
<span class="n">GeoJSON</span> <span class="p">(</span><span class="n">OGR</span><span class="p">)</span> <span class="mf">0.089</span><span class="n">s</span>
</pre></div>
</div>
</section>
<section id="spend-time-to-review-gdal-s-associated-driver-page-for-your-chosen-format">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Spend time to review GDAL’s associated driver page for your chosen format</a><a class="headerlink" href="#spend-time-to-review-gdal-s-associated-driver-page-for-your-chosen-format" title="Link to this heading">¶</a></h2>
<p>This is a critical step, as MapServer relies on GDAL (actually the OGR part of the
project, which handles vectors) for vector data access. Each driver (OGR format)
has its own set of abilities and switches. Find your vector format and review
its options <a class="reference external" href="https://gdal.org/drivers/vector/index.html">here</a>.</p>
</section>
<section id="connect-to-your-data-through-ogr-gdal">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Connect to your data through OGR/GDAL</a><a class="headerlink" href="#connect-to-your-data-through-ogr-gdal" title="Link to this heading">¶</a></h2>
<p>For data management in MapServer, this should always be one of your first steps.
Sometimes desktop GIS programs will display a format or its attributes in a certain
way (such as in uppercase) but your data might not display in MapServer; checking
how OGR/GDAL reads your data file or database table, will help you manage
the data. The <a class="reference internal" href="../input/vector/ogr.html#ogr"><span class="std std-ref">OGR Vector Layers Through MapServer</span></a> document has excellent examples
(for <em>ogrinfo</em> and other commands) to connect to your data. Here is an
example connecting to a PostGIS database, and returning a list of spatial tables:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>ogrinfo -ro PG:"host=127.0.0.1 user=postgres password=postgres port=5432 dbname=mydb"
INFO: Open of `PG:host=127.0.0.1 user=postgres password=postgres port=5432 dbname=mydb'
using driver `PostgreSQL' successful.
1: popplace (Point)
2: province (Multi Polygon)
</pre></div>
</div>
<p>Then get a summary of the “popplace” table through ogrinfo:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>ogrinfo -ro PG:"host=127.0.0.1 user=postgres password=postgres port=5433 dbname=mydb" popplace -summary
INFO: Open of `PG:host=127.0.0.1 user=postgres password=postgres port=5433 dbname=mydb'
using driver `PostgreSQL' successful.
Layer name: popplace
Geometry: Point
Feature Count: 497
Extent: (-2303861.750000, -681502.875000) - (2961766.250000, 3798856.750000)
Layer SRS WKT:
PROJCS["NAD83 / Canada Atlas Lambert",
GEOGCS["NAD83",
DATUM["North_American_Datum_1983",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6269"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4269"]],
PROJECTION["Lambert_Conformal_Conic_2SP"],
PARAMETER["standard_parallel_1",49],
PARAMETER["standard_parallel_2",77],
PARAMETER["latitude_of_origin",49],
PARAMETER["central_meridian",-95],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","3978"]]
FID Column = gid
Geometry Column = geom
area: Real (0.0)
perimeter: Real (0.0)
popplace_: Real (0.0)
popplace_i: Real (0.0)
unique_key: String (5.0)
name: String (25.0)
name_e: String (20.0)
name_f: String (20.0)
reg_code: Real (0.0)
nts50: String (7.0)
lat: String (7.0)
long: String (7.0)
sgc_code: Real (0.0)
capital: Real (0.0)
pop_range: Real (0.0)
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Nota</p>
<p>You can use the extent values returned from ogrinfo, to paste into your
mapfile’s EXTENT parameter. You can also notice in that summary
the <em>PROJCS/AUTHORITY</em> line, which states that this data is currently
in the <a class="reference external" href="https://spatialreference.org/ref/epsg/3978/">EPSG:3978</a> projection.</p>
</div>
</section>
<section id="learn-review-the-various-ogr-utilities-to-manage-your-vectors">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Learn & Review the various OGR utilities to manage your vectors</a><a class="headerlink" href="#learn-review-the-various-ogr-utilities-to-manage-your-vectors" title="Link to this heading">¶</a></h2>
<p>OGR commandline utilities are very useful, making it easy to manipulate
your source vector file or database, before display in MapServer. For example,
you might want to import a spatial file into your existing PostGIS database,
which you can do easily through
<a class="reference external" href="https://gdal.org/programs/ogr2ogr.html">ogr2ogr</a> as the following
(that takes a shapefile, imports it into an existing PostGIS database, and
renames the new table to “roadways”) :</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ogr2ogr</span> <span class="n">PG</span><span class="p">:</span><span class="s2">"host=127.0.0.1 user=postgres password=postgres port=5432 dbname=mydb"</span> <span class="n">road</span><span class="o">.</span><span class="n">shp</span> <span class="o">-</span><span class="n">nln</span> <span class="n">roadways</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Nota</p>
<p>where ogr2ogr syntax is actually: <em>ogr2ogr destination source</em></p>
</div>
<p>You might also import a spatial file, and reproject it to another EPSG
projection, as the following (that takes a shapefile, reprojects it into
the web mercator <a class="reference external" href="https://spatialreference.org/ref/epsg/3857/">EPSG:3857</a>, imports it into an
existing PostGIS database, and renames the new table to “roadways3857”) :</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ogr2ogr</span> <span class="o">-</span><span class="n">t_srs</span> <span class="n">EPSG</span><span class="p">:</span><span class="mi">3857</span> <span class="o">-</span><span class="n">s_srs</span> <span class="n">EPSG</span><span class="p">:</span><span class="mi">3978</span> <span class="n">PG</span><span class="p">:</span><span class="s2">"host=127.0.0.1 user=postgres password=postgres port=5432 dbname=mydb"</span> <span class="n">road</span><span class="o">.</span><span class="n">shp</span> <span class="o">-</span><span class="n">nln</span> <span class="n">roadways3857</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Nota</p>
<p>where ogr2ogr syntax is actually: <em>ogr2ogr -t_srs (ouput projection) -s_srs (source projection) destination source</em></p>
</div>
<p>Review all of the available OGR vector utilities
<a class="reference external" href="https://gdal.org/programs/#vector-programs">here</a>.</p>
</section>
<section id="index-your-data">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Index your data</a><a class="headerlink" href="#index-your-data" title="Link to this heading">¶</a></h2>
<p>This of course is an important step for any vector layer, for fast display
in MapServer. There are several types of indexes that you can enable to
speed up the display of your vector data with MapServer:</p>
<section id="tileindexing">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Tileindexing</a><a class="headerlink" href="#tileindexing" title="Link to this heading">¶</a></h3>
<p>See <a class="reference internal" href="tileindex.html#tileindex"><span class="std std-ref">Tile Indexes</span></a> for more detailed information about
on-the-fly mosaicing with MapServer.</p>
</section>
<section id="add-a-spatial-index-to-your-data">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Add a Spatial Index to your data</a><a class="headerlink" href="#add-a-spatial-index-to-your-data" title="Link to this heading">¶</a></h3>
<p>Make sure that your geometry has a spatial index.</p>
<ul class="simple">
<li><p>Shapefile: see <a class="reference internal" href="../utilities/shptree.html#shptree"><span class="std std-ref">shptree</span></a></p></li>
<li><p>See below for databases (and GPKG)</p></li>
</ul>
</section>
<section id="add-an-attribute-index-to-your-data">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Add an Attribute Index to your data</a><a class="headerlink" href="#add-an-attribute-index-to-your-data" title="Link to this heading">¶</a></h3>
<p>If you will be querying or filtering by a specific column in your
data, you should setup an attribute index on your vector data.</p>
<p>Shapefiles:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ogrinfo</span> <span class="o">-</span><span class="n">sql</span> <span class="s2">"CREATE INDEX ON province USING NAME_E"</span> <span class="n">province</span><span class="o">.</span><span class="n">shp</span>
</pre></div>
</div>
<p>2 files should be created with extensions: <em>.ind & .idm</em></p>
<p>GeoPackage:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ogrinfo</span> <span class="o">-</span><span class="n">sql</span> <span class="s2">"CREATE INDEX IDXnewindexname ON yourtable (yourcolumn)"</span> <span class="n">file</span><span class="o">.</span><span class="n">gpkg</span>
</pre></div>
</div>
</section>
</section>
<section id="splitting-your-data">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Splitting your data</a><a class="headerlink" href="#splitting-your-data" title="Link to this heading">¶</a></h2>
<p>If you find yourself making several layers, all of them using the same dataset
but filtering to only use some of the records, you could probably do it
better. If the criteria are static, one approach is to pre-split the data.</p>
<p>The <em>ogr2ogr</em> utility can select on certain features from a datasource, and
save them to a new data source. Thus, you can split your dataset into several
smaller ones that are already effectively filtered, and remove the FILTER
statement.</p>
<p>If you are using shapefiles, the <a class="reference external" href="https://github.com/woodbri/imaptools.com">shp2tile</a>
utility is a wonderful commandline tool for this.</p>
<div class="admonition note">
<p class="admonition-title">Nota</p>
<p>For Windows users, <a class="reference external" href="https://ms4w.com">MS4W</a> includes the shp2tile utility, and
all utilities mentioned here.</p>
</div>
</section>
<section id="handling-your-vector-layers-in-the-mapfile">
<span id="index-1"></span><h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Handling your vector LAYERS in the mapfile</a><a class="headerlink" href="#handling-your-vector-layers-in-the-mapfile" title="Link to this heading">¶</a></h2>
<p>Please review the notes in the document <a class="reference internal" href="mapfile.html#mapfile-tuning"><span class="std std-ref">Mapfile Tuning & Management</span></a>. You should also
check for any specific MapServer notes for your format in the <a class="reference internal" href="../input/vector/index.html#vector"><span class="std std-ref">Vector Data</span></a>
document.</p>
</section>
<section id="shapefile-notes">
<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Shapefile Notes</a><a class="headerlink" href="#shapefile-notes" title="Link to this heading">¶</a></h2>
<p>Use <a class="reference internal" href="../utilities/shptree.html#shptree"><span class="std std-ref">shptree</span></a> to generate a spatial index on your <a class="reference internal" href="../input/vector/shapefiles.html#shapefiles"><span class="std std-ref">shapefile</span></a>. This is
quick and easy («shptree foo.shp») and generates a .qix file. MapServer will
automagically detect an index and use it.</p>
<div class="admonition note">
<p class="admonition-title">Nota</p>
<p>Tileindexes can also be indexed with <a class="reference internal" href="../utilities/shptree.html#shptree"><span class="std std-ref">shptree</span></a>.</p>
</div>
<p>MapServer also comes with the <a class="reference internal" href="../utilities/sortshp.html#sortshp"><span class="std std-ref">sortshp</span></a> utility. This reorganizes a
shapefile, sorting it according to the values in one of its columns. If you’re
commonly filtering by criteria and it’s almost always by a specific column,
this can make the process slightly more efficient.</p>
<p>Although shapefiles are a very fast data format, <a class="reference internal" href="../input/vector/postgis.html#input-postgis"><span class="std std-ref">PostGIS</span></a> is pretty speedy as well, especially if you use indexes well
and have memory to throw at caching.</p>
</section>
<section id="postgis-notes">
<span id="index-2"></span><h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">PostGIS Notes</a><a class="headerlink" href="#postgis-notes" title="Link to this heading">¶</a></h2>
<div class="admonition seealso">
<p class="admonition-title">Vedi anche</p>
<p><a class="reference internal" href="../input/vector/postgis.html#input-postgis"><span class="std std-ref">PostGIS Input in MapServer</span></a></p>
</div>
<section id="indexing-with-postgis">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Indexing with PostGIS</a><a class="headerlink" href="#indexing-with-postgis" title="Link to this heading">¶</a></h3>
<p>The single biggest boost to performance is indexing. Make sure that there’s a
GIST index on the geometry column, and each record should also have an indexed
primary key. If you used shp2pgsql, then these statements should create the
necessary indexes:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="p">(</span><span class="n">gid</span><span class="p">);</span>
<span class="k">CREATE</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">table_the_geom</span><span class="w"> </span><span class="k">ON</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="p">(</span><span class="n">the_geom</span><span class="p">)</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="n">GIST</span><span class="p">;</span>
</pre></div>
</div>
<p>PostgreSQL also supports reorganizing the data in a table, such that it’s
physically sorted by the index. This allows PostgreSQL to be much more
efficient in reading the indexed data. Use the
<a class="reference external" href="https://www.postgresql.org/docs/current/sql-cluster.html">CLUSTER command</a>,
e.g.</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">CLUSTER</span><span class="w"> </span><span class="n">the_geom</span><span class="w"> </span><span class="k">ON</span><span class="w"> </span><span class="k">table</span><span class="p">;</span>
</pre></div>
</div>
<p>Then there are numerous optimizations one can perform on the database server
itself, aside from the geospatial component. The easiest is to increase
<em>shared_buffers</em> in the <em>postgresql.conf</em> file, which allows PostgreSQL to use
more memory for caching. It is worth the time to investigate the various options
in the <a class="reference external" href="https://www.postgresql.org/docs/current/runtime-config-resource.html">Resource Consumption</a>
section of the PostgreSQL documentation.</p>
</section>
<section id="specifying-a-unique-id-column">
<span id="uniqueid-postgis"></span><h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Specifying a Unique ID column</a><a class="headerlink" href="#specifying-a-unique-id-column" title="Link to this heading">¶</a></h3>
<p>To handle queries, MapServer requires a unique ID column, as part of your
PostgreSQL table. MapServer will try to guess the unique ID column, but that
is costly as several more database queries have to be made; instead, you should
always specify a unique ID column in your DATA statement of the layer, with the
<em>using unique</em> syntax, such as:</p>
<div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="k">DATA</span> <span class="s">"geom FROM mydata USING UNIQUE myid USING SRID=3857"</span>
</pre></div>
</div>
<p>If your table does not have a unique ID column, you can add one such as:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ALTER</span> <span class="n">TABLE</span> <span class="n">mytable</span> <span class="n">ADD</span> <span class="n">COLUMN</span> <span class="n">unique_id</span> <span class="n">SERIAL</span> <span class="n">PRIMARY</span> <span class="n">KEY</span><span class="p">;</span>
</pre></div>
</div>
<div class="admonition warning">
<p class="admonition-title">Avvertimento</p>
<p>In older PostgreSQL versions, a (dirty) trick was to use the existing <em>OID</em> as
the unique ID, however OIDs were removed from PostgreSQL as of the PostgreSQL 12.0 release.
So always specify an actual unique ID column instead, in your layer’s
DATA statement, of your mapfile.</p>
</div>
</section>
<section id="debugging-speed-issues-with-postgis">
<span id="debugging-postgis"></span><h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Debugging speed issues with PostGIS</a><a class="headerlink" href="#debugging-speed-issues-with-postgis" title="Link to this heading">¶</a></h3>
<p>You may face a situation where your PostGIS table is drawing slowly in MapServer.
The following steps will help you examine the issue (using a WFS case) :</p>
<div class="admonition seealso">
<p class="admonition-title">Vedi anche</p>
<p><a class="reference internal" href="debugging.html#debugging"><span class="std std-ref">Debugging MapServer</span></a></p>
</div>
<ul>
<li><p>Always start by getting the draw time for your layer, with a <a class="reference internal" href="../utilities/map2img.html#map2img"><span class="std std-ref">map2img</span></a>
command:</p>
<blockquote>
<div><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">map2img</span> <span class="o">-</span><span class="n">m</span> <span class="n">postgis</span><span class="o">-</span><span class="n">wfs</span><span class="o">.</span><span class="n">map</span> <span class="o">-</span><span class="n">o</span> <span class="n">ttt</span><span class="o">.</span><span class="n">png</span> <span class="o">-</span><span class="n">map_debug</span> <span class="mi">3</span>
<span class="n">msDrawMap</span><span class="p">():</span> <span class="n">Layer</span> <span class="mi">0</span> <span class="p">(</span><span class="n">provinces</span><span class="p">),</span> <span class="mf">1.587</span><span class="n">s</span>
<span class="n">msDrawMap</span><span class="p">():</span> <span class="n">Drawing</span> <span class="n">Label</span> <span class="n">Cache</span><span class="p">,</span> <span class="mf">0.000</span><span class="n">s</span>
<span class="n">msDrawMap</span><span class="p">()</span> <span class="n">total</span> <span class="n">time</span><span class="p">:</span> <span class="mf">1.589</span><span class="n">s</span>
<span class="n">msSaveImage</span><span class="p">(</span><span class="n">ttt</span><span class="o">.</span><span class="n">png</span><span class="p">)</span> <span class="n">total</span> <span class="n">time</span><span class="p">:</span> <span class="mf">0.005</span><span class="n">s</span>
<span class="n">freeLayer</span><span class="p">():</span> <span class="n">freeing</span> <span class="n">layer</span> <span class="n">at</span> <span class="mf">010E0</span><span class="n">EC0</span><span class="o">.</span>
<span class="n">msPostGISLayerIsOpen</span> <span class="n">called</span><span class="o">.</span>
<span class="n">msConnPoolClose</span><span class="p">(</span><span class="n">host</span><span class="o">=</span><span class="mf">127.0.0.1</span> <span class="n">user</span><span class="o">=</span><span class="n">postgres</span> <span class="n">password</span><span class="o">=</span><span class="n">postgres</span> <span class="n">port</span><span class="o">=</span><span class="mi">5432</span> <span class="n">dbname</span><span class="o">=</span><span class="n">gmap</span><span class="p">,</span><span class="mi">01197840</span><span class="p">)</span>
</pre></div>
</div>
</div></blockquote>
</li>
<li><p>To diagnose if the problem is with your PostGIS table configuration, or with
MapServer, execute the exact request sent by MapServer, at the psql.exe
commandline, by doing the following steps:</p>
<blockquote>
<div><ul>
<li><p>add into your MAP-level of your mapfile:</p>
<blockquote>
<div><div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="k">CONFIG</span> <span class="s">"CPL_DEBUG"</span> <span class="s">"ON"</span>
<span class="k">CONFIG</span> <span class="s">"MS_ERRORFILE"</span> <span class="s">"/ms4w/tmp/ms_error.txt"</span>
<span class="k">DEBUG</span> <span class="mi">5</span>
</pre></div>
</div>
</div></blockquote>
</li>
<li><p>add into your PostGIS LAYER of your mapfile:</p>
<blockquote>
<div><div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="k">DEBUG</span> <span class="mi">5</span>
</pre></div>
</div>
</div></blockquote>
</li>
<li><p>now use a WFS client such as QGIS and add your WFS PostGIS layer</p></li>
<li><p>open «/ms4w/tmp/ms_error.txt» in Notepad++</p></li>
<li><p>search for «msPostGISLayerWhichShapes query:»</p></li>
<li><p>that line should list the long exact query sent from MapServer to the
PostreSQL instance, it may look like:</p>
<blockquote>
<div><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="p">[</span><span class="n">Mon</span> <span class="n">Apr</span> <span class="mi">12</span> <span class="mi">11</span><span class="p">:</span><span class="mi">27</span><span class="p">:</span><span class="mi">34</span> <span class="mi">2021</span><span class="p">]</span><span class="mf">.207000</span> <span class="n">msPostGISLayerWhichShapes</span> <span class="n">query</span><span class="p">:</span>
<span class="n">SELECT</span> <span class="s2">"gid"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"area"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"perimeter"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"province_"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"province_i"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"status"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"name"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"name_e"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"name_f"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"reg_code"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"poly_featu"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"island"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"island_e"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"island_f"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="n">ST_AsBinary</span><span class="p">((</span><span class="s2">"geom"</span><span class="p">),</span><span class="s1">'NDR'</span><span class="p">)</span>
<span class="k">as</span> <span class="n">geom</span><span class="p">,</span><span class="s2">"gid"</span><span class="p">::</span><span class="n">text</span> <span class="n">FROM</span> <span class="n">province</span> <span class="n">WHERE</span> <span class="s2">"geom"</span> <span class="o">&&</span>
<span class="n">ST_GeomFromText</span><span class="p">(</span><span class="s1">'POLYGON((-5814679.36987815</span>
<span class="o">-</span><span class="mf">1504714.04276694</span><span class="p">,</span><span class="o">-</span><span class="mf">5814679.36987815</span> <span class="mf">4439806.52253364</span><span class="p">,</span><span class="mf">5943763.33635122</span>
<span class="mf">4439806.52253364</span><span class="p">,</span><span class="mf">5943763.33635122</span> <span class="o">-</span><span class="mf">1504714.04276694</span><span class="p">,</span><span class="o">-</span><span class="mf">5814679.36987815</span>
<span class="o">-</span><span class="mf">1504714.04276694</span><span class="p">))</span><span class="s1">',3978) LIMIT 2 OFFSET 0</span>
</pre></div>
</div>
</div></blockquote>
<div class="admonition note">
<p class="admonition-title">Nota</p>
<p>For one QGIS action, there could be several queries sent to MapServer,
so also look for other «msPostGISLayerWhichShapes query:» instances in
that error log.</p>
</div>
</li>
<li><p>now connect to that database through psql.exe</p>
<blockquote>
<div><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">psql</span> <span class="o">-</span><span class="n">U</span> <span class="n">postgres</span> <span class="o">-</span><span class="n">p</span> <span class="mi">5432</span> <span class="o">-</span><span class="n">d</span> <span class="n">mydb</span>
</pre></div>
</div>
</div></blockquote>
</li>
<li><p>using that error file line, grab everything from «SELECT», and inside
your database prompt, start the command with «EXPLAIN ANALYZE» and then
paste your full query, such as:</p>
<blockquote>
<div><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">mydb</span><span class="o">=</span><span class="c1"># EXPLAIN ANALYZE SELECT</span>
<span class="s2">"gid"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"area"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"perimeter"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"province_"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"province_i"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"status"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"name"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"name_e"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"name_f"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"reg_code"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"poly_featu"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"island"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"island_e"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="s2">"island_f"</span><span class="p">::</span><span class="n">text</span><span class="p">,</span><span class="n">ST_AsBinary</span><span class="p">((</span><span class="s2">"geom"</span><span class="p">),</span><span class="s1">'NDR'</span><span class="p">)</span>
<span class="k">as</span> <span class="n">geom</span><span class="p">,</span><span class="s2">"gid"</span><span class="p">::</span><span class="n">text</span> <span class="n">FROM</span> <span class="n">province</span> <span class="n">WHERE</span> <span class="s2">"geom"</span> <span class="o">&&</span>
<span class="n">ST_GeomFromText</span><span class="p">(</span><span class="s1">'POLYGON((-5814679.36987815</span>
<span class="o">-</span><span class="mf">1504714.04276694</span><span class="p">,</span><span class="o">-</span><span class="mf">5814679.36987815</span> <span class="mf">4439806.52253364</span><span class="p">,</span><span class="mf">5943763.33635122</span>
<span class="mf">4439806.52253364</span><span class="p">,</span><span class="mf">5943763.33635122</span> <span class="o">-</span><span class="mf">1504714.04276694</span><span class="p">,</span><span class="o">-</span><span class="mf">5814679.36987815</span>
<span class="o">-</span><span class="mf">1504714.04276694</span><span class="p">))</span><span class="s1">',3978) LIMIT 2 OFFSET 0;</span>
</pre></div>
</div>
</div></blockquote>
</li>
<li><p>the response will tell you how long that query took, such as:</p>
<blockquote>
<div><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">Execution</span> <span class="n">time</span><span class="p">:</span> <span class="mf">0.293</span> <span class="n">ms</span>
</pre></div>
</div>
</div></blockquote>
</li>
<li><p>if the query takes a long time to execute at the psql commandline, then you know
to focus your efforts on improving the indexing/settings of your PostGIS table.</p></li>
</ul>
</div></blockquote>
</li>
</ul>
</section>
</section>
<section id="databases-in-general-postgis-oracle-spatialite-geopackage-microsoft-sql-server-mysql">
<span id="vector-database-optimization"></span><span id="index-3"></span><h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Databases in General (PostGIS, Oracle, SpatiaLite, GeoPackage, Microsoft SQL Server, MySQL)</a><a class="headerlink" href="#databases-in-general-postgis-oracle-spatialite-geopackage-microsoft-sql-server-mysql" title="Link to this heading">¶</a></h2>
<section id="enable-connection-pooling">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Enable Connection Pooling</a><a class="headerlink" href="#enable-connection-pooling" title="Link to this heading">¶</a></h3>
<p>By default, MapServer opens and closes a new database connection for each
database-driven layer in the mapfile. If you have several layers reading from
the same database, this doesn’t make a lot of sense. And with some databases
(such as Oracle) establishing connections takes enough time that it can become
significant.</p>
<p>Try adding this line to your database layers:</p>
<div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="k">PROCESSING</span> <span class="s">"CLOSE_CONNECTION=DEFER"</span>
</pre></div>
</div>
<p>This causes MapServer to not close the database connection for each layer until
after it has finished processing the mapfile and this may shave a few seconds
off of map generation times.</p>
</section>
<section id="set-extent-at-the-layer-level-of-mapfile">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Set EXTENT at the LAYER level of mapfile</a><a class="headerlink" href="#set-extent-at-the-layer-level-of-mapfile" title="Link to this heading">¶</a></h3>
<p>Also for performance, each of your LAYERs with a database connection should
have <a class="reference internal" href="../mapfile/layer.html#layer-extent"><span class="std std-ref">EXTENT</span></a> set at the layer level (as well as <em>ows_extent</em> metadata if you
are serving through OGC services), such as:</p>
<blockquote>
<div><div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="cm">/* my database layer */</span>
<span class="k">LAYER</span>
<span class="k">NAME</span> <span class="s">"provinces"</span>
<span class="k">METADATA</span>
<span class="s">"wms_title"</span> <span class="s">"Land"</span>
<span class="s">"wms_extent"</span> <span class="s">"-2340603.75 -719746.0625 3009430.5 3836605.25"</span> <span class="c1">#this helps for performance</span>
<span class="k">END</span> <span class="c1">#metadata</span>
<span class="k">TYPE</span> <span class="nb">POLYGON</span>
<span class="k">STATUS</span> <span class="nb">ON</span>
<span class="k">CONNECTIONTYPE</span> <span class="nb">postgis</span>
<span class="k">CONNECTION</span> <span class="s">"host=127.0.0.1 user=postgres password=postgres port=5432 dbname=gmap"</span>
<span class="k">DATA</span> <span class="s">"geom FROM province USING unique gid using srid=3978"</span>
<span class="k">EXTENT</span> <span class="p">-</span><span class="mf">2340603.75</span> <span class="p">-</span><span class="mf">719746.0625</span> <span class="mf">3009430.5</span> <span class="mf">3836605.25</span> <span class="c1">#this helps for performance</span>
<span class="k">PROJECTION</span>
<span class="s">"init=epsg:3978"</span>
<span class="k">END</span> <span class="c1"># projection</span>
<span class="p">...</span>
<span class="k">END</span> <span class="c1"># layer</span>
</pre></div>
</div>
</div></blockquote>
<div class="admonition tip">
<p class="admonition-title">Suggerimento</p>
<p>PostGIS users can use the <a class="reference external" href="https://postgis.net/docs/ST_Extent.html">ST_Extent()</a>
spatial function to get the bounding box of a table, such as</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">SELECT</span> <span class="n">ST_Extent</span><span class="p">(</span><span class="n">geom</span><span class="p">)</span> <span class="k">as</span> <span class="n">table_extent</span> <span class="n">FROM</span> <span class="n">province</span><span class="p">;</span>
<span class="n">table_extent</span>
<span class="o">----------------------------------------------------</span>
<span class="n">BOX</span><span class="p">(</span><span class="o">-</span><span class="mf">2340603.75</span> <span class="o">-</span><span class="mf">719746.0625</span><span class="p">,</span><span class="mf">3009430.5</span> <span class="mf">3836605.25</span><span class="p">)</span>
<span class="p">(</span><span class="mi">1</span> <span class="n">row</span><span class="p">)</span>
</pre></div>
</div>
</div>
</section>
<section id="verify-that-your-table-has-a-spatial-index">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Verify that your table has a Spatial Index</a><a class="headerlink" href="#verify-that-your-table-has-a-spatial-index" title="Link to this heading">¶</a></h3>
<section id="postgresql-postgis-example">
<h4>PostgreSQL/PostGIS example<a class="headerlink" href="#postgresql-postgis-example" title="Link to this heading">¶</a></h4>
<p>Once connected through psql commandline, describe the table and
look for an «Indexes» section, mentioning geometry, such as:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">Indexes</span><span class="p">:</span>
<span class="s2">"province_pkey"</span> <span class="n">PRIMARY</span> <span class="n">KEY</span><span class="p">,</span> <span class="n">btree</span> <span class="p">(</span><span class="n">ogc_fid</span><span class="p">)</span>
<span class="s2">"province_wkb_geometry_geom_idx"</span> <span class="n">gist</span> <span class="p">(</span><span class="n">wkb_geometry</span><span class="p">)</span>
</pre></div>
</div>
</section>
<section id="geopackage-example">
<h4>GeoPackage example<a class="headerlink" href="#geopackage-example" title="Link to this heading">¶</a></h4>
<p>You can use <em>ogrinfo</em> to verify that your GPKG table’s geometry
has a spatial index, which is very important for performance
(look for <cite>HasSpatialIndex (Integer) = 1</cite> to confirm that the spatial
index exists) :</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ogrinfo</span> <span class="o">-</span><span class="n">sql</span> <span class="s2">"SELECT HasSpatialIndex('countries', 'GEOMETRY')"</span> <span class="n">countries</span><span class="o">.</span><span class="n">gpkg</span>
<span class="n">Layer</span> <span class="n">name</span><span class="p">:</span> <span class="n">SELECT</span>
<span class="n">Geometry</span><span class="p">:</span> <span class="n">Unknown</span> <span class="p">(</span><span class="nb">any</span><span class="p">)</span>
<span class="n">Feature</span> <span class="n">Count</span><span class="p">:</span> <span class="mi">1</span>
<span class="n">Layer</span> <span class="n">SRS</span> <span class="n">WKT</span><span class="p">:</span>
<span class="p">(</span><span class="n">unknown</span><span class="p">)</span>
<span class="n">HasSpatialIndex</span><span class="p">:</span> <span class="n">Integer</span> <span class="p">(</span><span class="mf">0.0</span><span class="p">)</span>
<span class="n">OGRFeature</span><span class="p">(</span><span class="n">SELECT</span><span class="p">):</span><span class="mi">0</span>
<span class="n">HasSpatialIndex</span> <span class="p">(</span><span class="n">Integer</span><span class="p">)</span> <span class="o">=</span> <span class="mi">1</span>
</pre></div>
</div>
<p>and then add a spatial index with ogrinfo :</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ogrinfo</span> <span class="o">-</span><span class="n">sql</span> <span class="s2">"SELECT CreateSpatialIndex('parcelle_graphique', 'geom')"</span> <span class="n">PARCELLES_GRAPHIQUES</span><span class="o">.</span><span class="n">gpkg</span>
</pre></div>
</div>
</section>
</section>
<section id="for-wfs-services-prevent-using-default-full-extent">
<h3><a class="toc-backref" href="#table-of-contents" role="doc-backlink">For WFS services, prevent using default/full extent</a><a class="headerlink" href="#for-wfs-services-prevent-using-default-full-extent" title="Link to this heading">¶</a></h3>
<p>For your database connections, MapServer may (by default) use the full
extents of your data while performing a query (which can cause slow responses
>30seconds). You should likely set the following layer METADATA to
disable this:</p>
<div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="k">METADATA</span>
<span class="s">"wfs_use_default_extent_for_getfeature"</span> <span class="s">"false"</span>
<span class="k">END</span>
</pre></div>
</div>
<p>Here is a fully enhanced layer example:</p>
<div class="highlight-mapfile notranslate"><div class="highlight"><pre><span></span><span class="k">LAYER</span>
<span class="k">NAME</span> <span class="s">"CLUS"</span>
<span class="k">METADATA</span>
<span class="s">"ows_title"</span> <span class="s">"CLUS"</span>
<span class="s">"ows_srs"</span> <span class="s">"EPSG:3857 EPSG:4326 EPSG:2154"</span>
<span class="s">"wfs_getfeature_formatlist"</span> <span class="s">"geojson"</span>
<span class="s">"wfs_geomtype"</span> <span class="s">"MultiPolygon"</span>
<span class="s">"gml_featureid"</span> <span class="s">"fid"</span>
<span class="s">"gml_include_items"</span> <span class="s">"all"</span>
<span class="s">"gml_types"</span> <span class="s">"auto"</span>
<span class="s">"wfs_extent"</span> <span class="s">"115134 6049690 1242200 7108930"</span> <span class="c1">#set to improve performance for all DB layers</span>
<span class="s">"wfs_use_default_extent_for_getfeature"</span> <span class="s">"false"</span> <span class="c1">#set to improve performance for all DB layers</span>
<span class="s">"ows_enable_request"</span> <span class="s">"*"</span>
<span class="k">END</span> <span class="c1">#metadata</span>
<span class="k">TYPE</span> <span class="nb">POLYGON</span>
<span class="k">CONNECTIONTYPE</span> <span class="nb">OGR</span>
<span class="k">CONNECTION</span> <span class="s">"C:/ms4w/apps/RPG_2-0_GPKG_LAMB93_FR-2019/PARCELLES_GRAPHIQUES.gpkg"</span>
<span class="k">DATA</span> <span class="s">"parcelle_graphique"</span>
<span class="k">EXTENT</span> <span class="mi">115134</span> <span class="mi">6049690</span> <span class="mi">1242200</span> <span class="mi">7108930</span> <span class="c1">#set to improve performance for all DB layers</span>
<span class="k">PROCESSING</span> <span class="s">"CLOSE_CONNECTION=DEFER"</span> <span class="c1">#set to improve performance for all DB layers</span>
<span class="k">STATUS</span> <span class="nb">ON</span>
<span class="k">PROJECTION</span>
<span class="s">"init=epsg:2154"</span>
<span class="k">END</span> <span class="c1">#proj</span>
<span class="k">COMPOSITE</span>
<span class="k">OPACITY</span> <span class="mi">100</span>
<span class="k">END</span> <span class="c1">#composite</span>
<span class="k">CLASS</span>
<span class="k">NAME</span> <span class="s">"CLUS"</span>
<span class="k">STYLE</span>
<span class="k">OUTLINECOLOR</span> <span class="mi">255</span> <span class="mi">0</span> <span class="mi">255</span>
<span class="k">END</span> <span class="c1">#style</span>
<span class="k">END</span> <span class="c1">#class</span>
<span class="k">END</span> <span class="c1">#layer</span>
</pre></div>
</div>
</section>
</section>
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<h3>Current Table Of Contents</h3>
<ul>
<li><a class="reference internal" href="#">Vector Data Management & Optimization</a><ul>
<li><a class="reference internal" href="#choose-the-right-vector-format-for-your-needs">Choose the right vector format for your needs</a></li>
<li><a class="reference internal" href="#spend-time-to-review-gdal-s-associated-driver-page-for-your-chosen-format">Spend time to review GDAL’s associated driver page for your chosen format</a></li>
<li><a class="reference internal" href="#connect-to-your-data-through-ogr-gdal">Connect to your data through OGR/GDAL</a></li>
<li><a class="reference internal" href="#learn-review-the-various-ogr-utilities-to-manage-your-vectors">Learn & Review the various OGR utilities to manage your vectors</a></li>
<li><a class="reference internal" href="#index-your-data">Index your data</a><ul>
<li><a class="reference internal" href="#tileindexing">Tileindexing</a></li>
<li><a class="reference internal" href="#add-a-spatial-index-to-your-data">Add a Spatial Index to your data</a></li>
<li><a class="reference internal" href="#add-an-attribute-index-to-your-data">Add an Attribute Index to your data</a></li>
</ul>
</li>
<li><a class="reference internal" href="#splitting-your-data">Splitting your data</a></li>
<li><a class="reference internal" href="#handling-your-vector-layers-in-the-mapfile">Handling your vector LAYERS in the mapfile</a></li>
<li><a class="reference internal" href="#shapefile-notes">Shapefile Notes</a></li>
<li><a class="reference internal" href="#postgis-notes">PostGIS Notes</a><ul>
<li><a class="reference internal" href="#indexing-with-postgis">Indexing with PostGIS</a></li>
<li><a class="reference internal" href="#specifying-a-unique-id-column">Specifying a Unique ID column</a></li>
<li><a class="reference internal" href="#debugging-speed-issues-with-postgis">Debugging speed issues with PostGIS</a></li>
</ul>
</li>
<li><a class="reference internal" href="#databases-in-general-postgis-oracle-spatialite-geopackage-microsoft-sql-server-mysql">Databases in General (PostGIS, Oracle, SpatiaLite, GeoPackage, Microsoft SQL Server, MySQL)</a><ul>
<li><a class="reference internal" href="#enable-connection-pooling">Enable Connection Pooling</a></li>
<li><a class="reference internal" href="#set-extent-at-the-layer-level-of-mapfile">Set EXTENT at the LAYER level of mapfile</a></li>
<li><a class="reference internal" href="#verify-that-your-table-has-a-spatial-index">Verify that your table has a Spatial Index</a><ul>
<li><a class="reference internal" href="#postgresql-postgis-example">PostgreSQL/PostGIS example</a></li>
<li><a class="reference internal" href="#geopackage-example">GeoPackage example</a></li>
</ul>
</li>
<li><a class="reference internal" href="#for-wfs-services-prevent-using-default-full-extent">For WFS services, prevent using default/full extent</a></li>
</ul>
</li>
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