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<!DOCTYPE html>

<head>

<title>Vector Data Management & Optimization — MapServer 8.6.1 documentation</title>

</head><body>

<tr>

</td>

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</table>

<h3>Navigation</h3>

<ul>

<a href="../genindex.html" title="General Index"

accesskey="I">index</a></li>

<a href="../utilities/index.html" title="Utilities"

accesskey="N">next</a> |</li>

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accesskey="P">previous</a> |</li>

<li class="nav-item nav-item-1"><a href="../documentation.html" >MapServer 8.6.1 Documentation</a> »</li>

<li class="nav-item nav-item-2"><a href="index.html" accesskey="U">Optimization</a> »</li>

<li class="nav-item nav-item-this"><a href="">Vector Data Management & Optimization</a></li>

</ul>

</div>

<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>

<dt class="field-odd">Author:</dt>

<dd class="field-odd">Jeff McKenna

</dd>

<dt class="field-even">Contact:</dt>

<dd class="field-even">jmckenna at gatewaygeomatics.com

</dd>

<dt class="field-odd">Original Author:</dt>

<dd class="field-odd">HostGIS

</dd>

<dt class="field-even">Last Updated:</dt>

<dd class="field-even">2026-03-29

</dd>

</dl>

Table of Contents

<li><a class="reference internal" href="#vector-data-management-optimization" id="id1">Vector Data Management & Optimization</a>

<ul>

<li><a class="reference internal" href="#choose-the-right-vector-format-for-your-needs" id="id2">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" id="id3">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" id="id4">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" id="id5">Learn & Review the various OGR utilities to manage your vectors</a></li>

<li><a class="reference internal" href="#index-your-data" id="id6">Index your data</a>

<ul>

<li><a class="reference internal" href="#tileindexing" id="id7">Tileindexing</a></li>

<li><a class="reference internal" href="#add-a-spatial-index-to-your-data" id="id8">Add a Spatial Index to your data</a></li>

<li><a class="reference internal" href="#add-an-attribute-index-to-your-data" id="id9">Add an Attribute Index to your data</a></li>

</ul>

</li>

<li><a class="reference internal" href="#splitting-your-data" id="id10">Splitting your data</a></li>

<li><a class="reference internal" href="#handling-your-vector-layers-in-the-mapfile" id="id11">Handling your vector LAYERS in the mapfile</a></li>

<li><a class="reference internal" href="#shapefile-notes" id="id12">Shapefile Notes</a></li>

<li><a class="reference internal" href="#postgis-notes" id="id13">PostGIS Notes</a>

<ul>

<li><a class="reference internal" href="#indexing-with-postgis" id="id14">Indexing with PostGIS</a></li>

<li><a class="reference internal" href="#specifying-a-unique-id-column" id="id15">Specifying a Unique ID column</a></li>

<li><a class="reference internal" href="#debugging-speed-issues-with-postgis" id="id16">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" id="id17">Databases in General (PostGIS, Oracle, SpatiaLite, GeoPackage, Microsoft SQL Server, MySQL)</a>

<ul>

<li><a class="reference internal" href="#enable-connection-pooling" id="id18">Enable Connection Pooling</a></li>

<li><a class="reference internal" href="#set-extent-at-the-layer-level-of-mapfile" id="id19">Set EXTENT at the LAYER level of mapfile</a></li>

<li><a class="reference internal" href="#verify-that-your-table-has-a-spatial-index" id="id20">Verify that your table has a Spatial Index</a></li>

<li><a class="reference internal" href="#for-wfs-services-prevent-using-default-full-extent" id="id21">For WFS services, prevent using default/full extent</a></li>

</ul>

</li>

</ul>

</li>

</ul>

</nav>

<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>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">Shapefile</a>.

Tip

MapServer 8.0 includes a new <a class="reference internal" href="../utilities/coshp.html#coshp">coshp</a> utility to create

‘Cloud Optimized Shapefiles’

</div>

</li>

<li>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">FlatGeobuf</a>, and is

recommended for cloud performance.</li>

<li>For databases, MapServer displays <a class="reference internal" href="../input/vector/postgis.html#input-postgis">PostGIS</a>

layers very fast, and some custom tricks are included in the MapServer source

specifically for PostGIS + MapServer draw speed. PostGIS is therefore recommended.</li>

<li><a class="reference internal" href="../input/vector/sqlite.html#sqlite">SpatiaLite</a> is recommended

for those who require a portable format, and works very well with MapServer.</li>

<li><a class="reference internal" href="../input/vector/geopackage.html#geopackage">GeoPackage</a> (“GPKG”) is also very popular for portability,

and works very well with MapServer.</li>

</ul>

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>):

<div class="highlight-default notranslate"><div class="highlight"><pre>FlatGeobuf (native) 0.008s

Shapefile (native) 0.010s

FlatGeobuf (OGR) 0.013s

Shapefile (OGR) 0.023s

GeoPackage (OGR) 0.042s

SpatiaLite (OGR) 0.045s

PostGIS (native) 0.053s

GeoJSON (OGR) 0.089s

</pre></div>

</div>

</section>

<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>

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>.

</section>

<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>

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">OGR Vector Layers Through MapServer</a> document has excellent examples

(for ogrinfo and other commands) to connect to your data. Here is an

example connecting to a PostGIS database, and returning a list of spatial tables:

<div class="highlight-default notranslate"><div class="highlight"><pre>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>

Then get a summary of the ‘popplace’ table through ogrinfo:

<div class="highlight-default notranslate"><div class="highlight"><pre>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>

Note

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 PROJCS/AUTHORITY 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.

</div>

</section>

<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>

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’) :

<div class="highlight-default notranslate"><div class="highlight"><pre>ogr2ogr PG:"host=127.0.0.1 user=postgres password=postgres port=5432 dbname=mydb" road.shp -nln roadways

</pre></div>

</div>

Note

where ogr2ogr syntax is actually: ogr2ogr destination source

</div>

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’) :

<div class="highlight-default notranslate"><div class="highlight"><pre>ogr2ogr -t_srs EPSG:3857 -s_srs EPSG:3978 PG:"host=127.0.0.1 user=postgres password=postgres port=5432 dbname=mydb" road.shp -nln roadways3857

</pre></div>

</div>

Note

where ogr2ogr syntax is actually: ogr2ogr -t_srs (ouput projection) -s_srs (source projection) destination source

</div>

Review all of the available OGR vector utilities

<a class="reference external" href="https://gdal.org/programs/#vector-programs">here</a>.

</section>

<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>

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:

<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>

See <a class="reference internal" href="tileindex.html#tileindex">Tile Indexes</a> for more detailed information about

on-the-fly mosaicing with MapServer.

</section>

<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>

Make sure that your geometry has a spatial index.

<li>Shapefile: see <a class="reference internal" href="../utilities/shptree.html#shptree">shptree</a></li>

<li>See below for databases (and GPKG)</li>

</ul>

</section>

<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>

If you will be querying or filtering by a specific column in your

data, you should setup an attribute index on your vector data.

Shapefiles:

<div class="highlight-default notranslate"><div class="highlight"><pre>ogrinfo -sql "CREATE INDEX ON province USING NAME_E" province.shp

</pre></div>

</div>

2 files should be created with extensions: .ind & .idm

GeoPackage:

<div class="highlight-default notranslate"><div class="highlight"><pre>ogrinfo -sql "CREATE INDEX IDXnewindexname ON yourtable (yourcolumn)" file.gpkg

</pre></div>

</div>

</section>

<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>

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.

The ogr2ogr 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.

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.

Note

For Windows users, <a class="reference external" href="https://ms4w.com">MS4W</a> includes the shp2tile utility, and

all utilities mentioned here.

</div>

</section>

<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>

Please review the notes in the document <a class="reference internal" href="mapfile.html#mapfile-tuning">Mapfile Tuning & Management</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">Vector Data</a>

document.

</section>

<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>

Use <a class="reference internal" href="../utilities/shptree.html#shptree">shptree</a> to generate a spatial index on your <a class="reference internal" href="../input/vector/shapefiles.html#shapefiles">shapefile</a>. This is

quick and easy (“shptree foo.shp”) and generates a .qix file. MapServer will

automagically detect an index and use it.

Note

Tileindexes can also be indexed with <a class="reference internal" href="../utilities/shptree.html#shptree">shptree</a>.

</div>

MapServer also comes with the <a class="reference internal" href="../utilities/sortshp.html#sortshp">sortshp</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.

Although shapefiles are a very fast data format, <a class="reference internal" href="../input/vector/postgis.html#input-postgis">PostGIS</a> is pretty speedy as well, especially if you use indexes well

and have memory to throw at caching.

</section>

<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>

See also

<a class="reference internal" href="../input/vector/postgis.html#input-postgis">PostGIS Input in MapServer</a>

</div>

<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>

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:

<div class="highlight-sql notranslate"><div class="highlight"><pre>ALTER TABLE table ADD PRIMARY KEY (gid);

CREATE INDEX table_the_geom ON table (the_geom) USING GIST;

</pre></div>

</div>

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.

<div class="highlight-sql notranslate"><div class="highlight"><pre>CLUSTER the_geom ON table;

</pre></div>

</div>

Then there are numerous optimizations one can perform on the database server

itself, aside from the geospatial component. The easiest is to increase

shared_buffers in the postgresql.conf 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.

</section>

<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>

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

using unique syntax, such as:

<div class="highlight-mapfile notranslate"><div class="highlight"><pre>DATA "geom FROM mydata USING UNIQUE myid USING SRID=3857"

</pre></div>

</div>

If your table does not have a unique ID column, you can add one such as:

<div class="highlight-default notranslate"><div class="highlight"><pre>ALTER TABLE mytable ADD COLUMN unique_id SERIAL PRIMARY KEY;

</pre></div>

</div>

Warning

In older PostgreSQL versions, a (dirty) trick was to use the existing OID 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.

</div>

</section>

<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>

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) :

See also

<a class="reference internal" href="debugging.html#debugging">Debugging MapServer</a>

</div>

<ul>

<li>Always start by getting the draw time for your layer, with a <a class="reference internal" href="../utilities/map2img.html#map2img">map2img</a>

command:

<div><div class="highlight-default notranslate"><div class="highlight"><pre>map2img -m postgis-wfs.map -o ttt.png -map_debug 3

msDrawMap(): Layer 0 (provinces), 1.587s

msDrawMap(): Drawing Label Cache, 0.000s

msDrawMap() total time: 1.589s

msSaveImage(ttt.png) total time: 0.005s

freeLayer(): freeing layer at 010E0EC0.

msPostGISLayerIsOpen called.

msConnPoolClose(host=127.0.0.1 user=postgres password=postgres port=5432 dbname=gmap,01197840)

</pre></div>

</div>

</div></blockquote>

</li>

<li>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:

<li>add into your MAP-level of your mapfile:

<div><div class="highlight-mapfile notranslate"><div class="highlight"><pre>CONFIG "CPL_DEBUG" "ON"

CONFIG "MS_ERRORFILE" "/ms4w/tmp/ms_error.txt"

DEBUG 5

</pre></div>

</div>

</div></blockquote>

</li>

<li>add into your PostGIS LAYER of your mapfile:

<div><div class="highlight-mapfile notranslate"><div class="highlight"><pre>DEBUG 5

</pre></div>

</div>

</div></blockquote>

</li>

<li>now use a WFS client such as QGIS and add your WFS PostGIS layer</li>

<li>open “/ms4w/tmp/ms_error.txt” in Notepad++</li>

<li>search for “msPostGISLayerWhichShapes query:”</li>

<li>that line should list the long exact query sent from MapServer to the

PostreSQL instance, it may look like:

<div><div class="highlight-default notranslate"><div class="highlight"><pre>[Mon Apr 12 11:27:34 2021].207000 msPostGISLayerWhichShapes query:

SELECT "gid"::text,"area"::text,"perimeter"::text,"province_"::text,"province_i"::text,"status"::text,"name"::text,"name_e"::text,"name_f"::text,"reg_code"::text,"poly_featu"::text,"island"::text,"island_e"::text,"island_f"::text,ST_AsBinary(("geom"),'NDR')

as geom,"gid"::text FROM province WHERE "geom" &&

ST_GeomFromText('POLYGON((-5814679.36987815

-1504714.04276694,-5814679.36987815 4439806.52253364,5943763.33635122

4439806.52253364,5943763.33635122 -1504714.04276694,-5814679.36987815

-1504714.04276694))',3978) LIMIT 2 OFFSET 0

</pre></div>

</div>

</div></blockquote>

Note

For one QGIS action, there could be several queries sent to MapServer,

so also look for other “msPostGISLayerWhichShapes query:” instances in

that error log.

</div>

</li>

<li>now connect to that database through psql.exe

<div><div class="highlight-default notranslate"><div class="highlight"><pre>psql -U postgres -p 5432 -d mydb

</pre></div>

</div>

</div></blockquote>

</li>

<li>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:

<div><div class="highlight-default notranslate"><div class="highlight"><pre>mydb=# EXPLAIN ANALYZE SELECT

"gid"::text,"area"::text,"perimeter"::text,"province_"::text,"province_i"::text,"status"::text,"name"::text,"name_e"::text,"name_f"::text,"reg_code"::text,"poly_featu"::text,"island"::text,"island_e"::text,"island_f"::text,ST_AsBinary(("geom"),'NDR')

ST_GeomFromText('POLYGON((-5814679.36987815

-1504714.04276694))',3978) LIMIT 2 OFFSET 0;

</pre></div>

</div>

</div></blockquote>

</li>

<li>the response will tell you how long that query took, such as:

<div><div class="highlight-default notranslate"><div class="highlight"><pre>Execution time: 0.293 ms

</pre></div>

</div>

</div></blockquote>

</li>

<li>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.</li>

</ul>

</div></blockquote>

</li>

</ul>

</section>

<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>

<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>

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.

Try adding this line to your database layers:

<div class="highlight-mapfile notranslate"><div class="highlight"><pre>PROCESSING "CLOSE_CONNECTION=DEFER"

</pre></div>

</div>

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.

</section>

<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>

Also for performance, each of your LAYERs with a database connection should

have <a class="reference internal" href="../mapfile/layer.html#layer-extent">EXTENT</a> set at the layer level (as well as ows_extent metadata if you

are serving through OGC services), such as:

<div><div class="highlight-mapfile notranslate"><div class="highlight"><pre>/* my database layer */

LAYER

NAME "provinces"

METADATA

"wms_title" "Land"

"wms_extent" "-2340603.75 -719746.0625 3009430.5 3836605.25" #this helps for performance

END #metadata

TYPE POLYGON

STATUS ON

CONNECTIONTYPE postgis

CONNECTION "host=127.0.0.1 user=postgres password=postgres port=5432 dbname=gmap"

DATA "geom FROM province USING unique gid using srid=3978"

EXTENT -2340603.75 -719746.0625 3009430.5 3836605.25 #this helps for performance

PROJECTION

"init=epsg:3978"

END # projection

...

END # layer

</pre></div>

</div>

</div></blockquote>

Tip

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

<div class="highlight-default notranslate"><div class="highlight"><pre>SELECT ST_Extent(geom) as table_extent FROM province;

table_extent

----------------------------------------------------

BOX(-2340603.75 -719746.0625,3009430.5 3836605.25)

(1 row)

</pre></div>

</div>

</section>

<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>

<h4>PostgreSQL/PostGIS example<a class="headerlink" href="#postgresql-postgis-example" title="Link to this heading">¶</a></h4>

Once connected through psql commandline, describe the table and

look for an “Indexes” section, mentioning geometry, such as:

<div class="highlight-default notranslate"><div class="highlight"><pre>Indexes:

"province_pkey" PRIMARY KEY, btree (ogc_fid)

"province_wkb_geometry_geom_idx" gist (wkb_geometry)

</pre></div>

</div>

</section>

<h4>GeoPackage example<a class="headerlink" href="#geopackage-example" title="Link to this heading">¶</a></h4>

You can use ogrinfo 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) :

<div class="highlight-default notranslate"><div class="highlight"><pre>ogrinfo -sql "SELECT HasSpatialIndex('countries', 'GEOMETRY')" countries.gpkg

Layer name: SELECT

Geometry: Unknown (any)

Feature Count: 1

Layer SRS WKT:

(unknown)

HasSpatialIndex: Integer (0.0)

OGRFeature(SELECT):0

HasSpatialIndex (Integer) = 1

</pre></div>

</div>

and then add a spatial index with ogrinfo :

<div class="highlight-default notranslate"><div class="highlight"><pre>ogrinfo -sql "SELECT CreateSpatialIndex('parcelle_graphique', 'geom')" PARCELLES_GRAPHIQUES.gpkg

</pre></div>

</div>

</section>

<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>

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:

<div class="highlight-mapfile notranslate"><div class="highlight"><pre>METADATA

"wfs_use_default_extent_for_getfeature" "false"

END

</pre></div>

</div>

Here is a fully enhanced layer example:

<div class="highlight-mapfile notranslate"><div class="highlight"><pre>LAYER

NAME "CLUS"

METADATA

"ows_title" "CLUS"

"ows_srs" "EPSG:3857 EPSG:4326 EPSG:2154"

"wfs_getfeature_formatlist" "geojson"

"wfs_geomtype" "MultiPolygon"

"gml_featureid" "fid"

"gml_include_items" "all"

"gml_types" "auto"

"wfs_extent" "115134 6049690 1242200 7108930" #set to improve performance for all DB layers

"wfs_use_default_extent_for_getfeature" "false" #set to improve performance for all DB layers

"ows_enable_request" "*"

END #metadata

TYPE POLYGON

CONNECTIONTYPE OGR

CONNECTION "C:/ms4w/apps/RPG_2-0_GPKG_LAMB93_FR-2019/PARCELLES_GRAPHIQUES.gpkg"

DATA "parcelle_graphique"

EXTENT 115134 6049690 1242200 7108930 #set to improve performance for all DB layers

PROCESSING "CLOSE_CONNECTION=DEFER" #set to improve performance for all DB layers

STATUS ON

PROJECTION

"init=epsg:2154"

END #proj

COMPOSITE

OPACITY 100

END #composite

CLASS

NAME "CLUS"

STYLE

OUTLINECOLOR 255 0 255

END #style

END #class

END #layer

</pre></div>

</div>

</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>

</ul>

</li>

</ul>

</div>

</div>

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