Name
ST_MemSize — 返回几何体占用的内存空间量。
Synopsis
integer
ST_MemSize
(
geometry
geomA
)
;
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。
![[Note]](images/note.png)
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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