ST_explode-PolarDB(PolarDB)-阿里云帮助中心

Expands a pcpatch into a set of pcpoint rows, returning one row per point in the patch.

Syntax

setof[pcpoint] ST_explode(pcpatch pc)

Parameters

Parameter	Type	Description
`pc`	`pcpatch`	The patch to expand.

Example

SELECT ST_AsText(ST_Explode(pa)), id FROM patches WHERE id = 7;

Output:

              st_astext               | id
--------------------------------------+----
 {"pcid":1,"pt":[-126.5,45.5,50,5]}   |  7
 {"pcid":1,"pt":[-126.49,45.51,51,5]} |  7
 {"pcid":1,"pt":[-126.48,45.52,52,5]} |  7
 {"pcid":1,"pt":[-126.47,45.53,53,5]} |  7
 {"pcid":1,"pt":[-126.46,45.54,54,5]} |  7
 {"pcid":1,"pt":[-126.45,45.55,55,5]} |  7
 {"pcid":1,"pt":[-126.44,45.56,56,5]} |  7
 {"pcid":1,"pt":[-126.43,45.57,57,5]} |  7
 {"pcid":1,"pt":[-126.42,45.58,58,5]} |  7
 {"pcid":1,"pt":[-126.41,45.59,59,5]} |  7

ST_Explode is a set-returning function. Each call returns one pcpoint row per point in the patch. The query wraps ST_Explode in ST_AsText to render each point as a JSON string. Ten rows are returned because patch 7 contains ten points.