PostGIS

ST_MemSize
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ST_MemSize

8.4. Geometry Accessors

Name

ST_MemSize — Returns the amount of memory space a geometry takes.

Synopsis

integer +`*`+ST_MemSize*(`geometry `geomA`)`;

Description

Returns the amount of memory space (in bytes) the geometry takes.

This complements the PostgreSQL built-in database object functions pg_column_size, pg_size_pretty, pg_relation_size, pg_total_relation_size.

pg_relation_size which gives the byte size of a table may return byte size lower than ST_MemSize. This is because pg_relation_size does not add toasted table contribution and large geometries are stored in TOAST tables.

pg_total_relation_size - includes, the table, the toasted tables, and the indexes.

pg_column_size returns how much space a geometry would take in a column considering compression, so may be lower than ST_MemSize

check This function supports 3d and will not drop the z-index.

check This method supports Circular Strings and Curves

check This function supports Polyhedral surfaces.

check This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).

Changed: 2.2.0 name changed to ST_MemSize to follow naming convention.

Examples

--Return how much byte space Boston takes up  in our Mass data set
SELECT pg_size_pretty(SUM(ST_MemSize(geom))) as totgeomsum,
pg_size_pretty(SUM(CASE WHEN town = 'BOSTON' THEN ST_MemSize(geom) ELSE 0 END)) As bossum,
CAST(SUM(CASE WHEN town = 'BOSTON' THEN ST_MemSize(geom) ELSE 0 END)*1.00 /
        SUM(ST_MemSize(geom))*100 As numeric(10,2)) As perbos
FROM towns;

totgeomsum  bossum  perbos
----------  ------  ------
1522 kB     30 kB   1.99


SELECT ST_MemSize(ST_GeomFromText('CIRCULARSTRING(220268 150415,220227 150505,220227 150406)'));

---
73

--What percentage of our table is taken up by just the geometry
SELECT pg_total_relation_size('public.neighborhoods') As fulltable_size, sum(ST_MemSize(geom)) As geomsize,
sum(ST_MemSize(geom))*1.00/pg_total_relation_size('public.neighborhoods')*100 As pergeom
FROM neighborhoods;
fulltable_size geomsize  pergeom
------------------------------------------------
262144         96238     36.71188354492187500000

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