WL#8543: Mutator ST_SRID
Affects: Server-8.0 — Status: Complete
Add a mutator ST_SRID function that changes the SRID of a geometric object without changing/transforming the contents, according to ISO/IEC 13249-3:2011 Sect. 5.1.5. This function is especially valuable when we introduce geography support and users want to tell which SRS their data is in: UPDATE t1 SET geometry_column=ST_SRID(geometry_column, 4326); PostGIS has implemented this with a non-standard name: http://postgis.net/docs/ST_SetSRID.html MySQL already has an ST_SRID observer function.
Unless otherwise specified, the term "ST_SRID" in this section refers to the two parameter mutator function, not the observer function. Functional requirements: F-1: ST_SRID MUST return NULL if either argument is NULL. F-2: ST_SRID MUST NOT return NULL if neither argument is NULL. F-3: If the geometry argument is not a syntactically well-formed geometry, ST_SRID MUST raise ER_GIS_INVALID_DATA during function evaluation. F-4: If the SRID argument is not within the range of an unsigned 32 bit integer, ST_SRID MUST raise ER_DATA_OUT_OF_RANGE during function evaluation. F-5: If the SRID doesn't refer to a spatial reference system, ST_SRID MUST raise ER_SRS_NOT_FOUND (see definition below) during function evaluation. F-6: If the geometry argument is a valid geometry and the SRID is within range, ST_SRID MUST return an object of the same type as the input geometry. Non-functional requirements: NF-1: The function MUST be non-nullable if both arguments are non-nullable.
I-1: No new files. I-2: Interface SQL02 is extended with a new two-parameter form of ST_SRID: <geometry> = ST_SRID(<geometry>, <srid>). I-3: No new commands. I-4: No new tools. I-5: No impact on existing functionality. I-6: Interface ERR01 is extended with a new error message: ER_SRS_NOT_FOUND, SQLSTATE SR001, "There's no spatial reference system with SRID %u." I-7: No new warnings.
Create a new Item_func_set_srid, subclass of Item_geometry_func, that sets the SRID value. Parse the geometry string to verify that it is well-formed. Return ER_GIS_INVALID_DATA if it isn't. Validate the SRID using validate_srid_arg() and check that the SRID exists in the data dictionary. Return ER_SRS_NOT_FOUND if it's not defined. Rename Item_func_srid to Item_func_get_srid and modify Create_func_srid to accept both 1 and 2 argument forms of ST_SRID() and create the corresponding item.
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