ST_ValidateOSGB-PolarDB(PolarDB)-阿里云帮助中心

ST_ValidateOSGB checks the integrity of an OSGB oblique photography dataset stored in Object Storage Service (OSS), reporting any missing or error files. Run this function before importing data with ST_ImportOSGB to confirm data integrity, or after a failed import to identify the problem files.

Syntax

record ST_ValidateOSGB(cstring url, cstring options default '{}', out valid boolean, out reason text);

Parameters

Parameter	Description
`url`	The OSS path to the oblique photography project directory.
`options`	Validation options as a JSON string. Defaults to `'{}'`. See Options.

Return values

Field	Type	Description
`valid`	boolean	`true` if the OSGB dataset is intact; `false` if any files are missing or contain errors.
`reason`	text	A description of the missing or error files. Returns `NULL` if `valid` is `true`.

Options

Option	Type	Default	Description
`parallel`	Integer	`1`	The degree of parallelism (DOP) for validation. Higher values speed up validation but use more memory. Set to a value below `16`. Values below `1` are ignored.
`exclude`	String	—	Skips OSGB files whose file paths contain this string. For example, `Tile_A` excludes all files with `Tile_A` in their path.
`include`	String	—	Validates only OSGB files whose file paths contain this string. For example, `Tile_B` validates only files with `Tile_B` in their path.

Usage notes

ST_ValidateOSGB scans the OSGB dataset in OSS and identifies two categories of issues:

Missing files: OSGB files that no longer exist in OSS.
File errors: OSGB files that exist but are unreadable or contain errors.

Use this function in two situations:

Before import: Run validation to confirm data integrity before calling ST_ImportOSGB. Missing or error files are a common cause of import failures, and validating first lets you resolve them before they block the import.
After a failed import: When ST_ImportOSGB reports errors, run ST_ValidateOSGB first to pinpoint the problem files before retrying.

Examples

Basic validation

SELECT ST_ValidateOSGB('OSS://<ak>:<ak_secret>@oss-cn-beijing-internal.aliyuncs.com/mybucket/path_to_oblique_project/');

Example output when validation fails:

 f       | Missing or error file(s):                                     +
         |         /Data/Tile_+006_+004/Tile_+006_+004_L19_000000t3.osgb +
         |         /Data/Tile_+006_+004/Tile_+006_+004_L20_0000130t3.osgb+
         |         /Data/Tile_+006_+004/Tile_+006_+004_L21_00001110.osgb +

Validation with parallel processing

Set parallel to speed up validation of large datasets.

SELECT ST_ValidateOSGB('OSS://<ak>:<ak_secret>@oss-cn-beijing-internal.aliyuncs.com/mybucket/path_to_oblique_project/', '{"parallel": 4}');

Example output when validation fails:

 f       | Missing or error file(s):                                     +
         |         /Data/Tile_+006_+004/Tile_+006_+004_L19_000000t3.osgb +
         |         /Data/Tile_+006_+004/Tile_+006_+004_L20_0000130t3.osgb+
         |         /Data/Tile_+006_+004/Tile_+006_+004_L21_00001110.osgb +

What's next

After the dataset passes validation, import it into your database with ST_ImportOSGB.