描述

返回几何体占用的内存空间量(以字节为单位)。

这是对PostgreSQL内置功能的补充 数据库对象函数 PG_Column_Size、PG_Size_Pretty、PG_Relationship_Size、PG_Total_Relationship_Size。

	给出表的字节大小的PG_Relationship_SIZE可能返回小于ST_MemSize的字节大小。这是因为PG_Relationship_SIZE不添加烤面包表贡献，并且大几何图形存储在烤面包表中。 PG_TOTAL_RELATION_SIZE-包括、表、烤面包表和索引。 PG_COLUMN_SIZE返回考虑压缩后几何在列中所占的空间量，因此可能低于ST_MemSize

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

This method supports Circular Strings and Curves

This function supports Polyhedral surfaces.

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

已更改：2.2.0名称更改为ST_MemSize以遵循命名约定。

示例

--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