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It seems potentially useful to label our shared libraries with version information, now that a facility exists for retrieving that. This patch labels them with the PG_VERSION string. There was some discussion about using semantic versioning conventions, but that doesn't seem terribly helpful for modules with no SQL-level presence; and for those that do have SQL objects, we typically expect them to support multiple revisions of the SQL definitions, so it'd still not be very helpful. I did not label any of src/test/modules/. It seems unnecessary since we don't install those, and besides there ought to be someplace that still provides test coverage for the original PG_MODULE_MAGIC macro. Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/dd4d1b59-d0fe-49d5-b28f-1e463b68fa32@gmail.com
46 lines
1.0 KiB
C
46 lines
1.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_freespacemap.c
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* display contents of a free space map
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*
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* contrib/pg_freespacemap/pg_freespacemap.c
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/relation.h"
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#include "fmgr.h"
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#include "storage/freespace.h"
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PG_MODULE_MAGIC_EXT(
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.name = "pg_freespacemap",
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.version = PG_VERSION
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);
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/*
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* Returns the amount of free space on a given page, according to the
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* free space map.
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*/
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PG_FUNCTION_INFO_V1(pg_freespace);
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Datum
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pg_freespace(PG_FUNCTION_ARGS)
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{
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Oid relid = PG_GETARG_OID(0);
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int64 blkno = PG_GETARG_INT64(1);
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int16 freespace;
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Relation rel;
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rel = relation_open(relid, AccessShareLock);
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if (blkno < 0 || blkno > MaxBlockNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid block number")));
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freespace = GetRecordedFreeSpace(rel, blkno);
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relation_close(rel, AccessShareLock);
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PG_RETURN_INT16(freespace);
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}
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