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Code and docs review for pg_column_size() patch.

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This commit is contained in:
Tom Lane
2005-08-02 16:11:57 +00:00
parent f023fc6689
commit 0001e98d54
4 changed files with 130 additions and 108 deletions
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49
src/backend/utils/adt/varlena.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.130 2005/07/29 03:17:55 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.131 2005/08/02 16:11:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2574,38 +2574,49 @@ md5_bytea(PG_FUNCTION_ARGS)
}
/*
* Return the length of a datum, possibly compressed
* Return the size of a datum, possibly compressed
*
* Works on any data type
*/
Datum
pg_column_size(PG_FUNCTION_ARGS)
{
Datum value = PG_GETARG_DATUM(0);
int result;
Datum value = PG_GETARG_DATUM(0);
int32 result;
int typlen;
/* fn_extra stores the fixed column length, or -1 for varlena. */
if (fcinfo->flinfo->fn_extra == NULL) /* first call? */
/* On first call, get the input type's typlen, and save at *fn_extra */
if (fcinfo->flinfo->fn_extra == NULL)
{
/* On the first call lookup the datatype of the supplied argument */
Oid argtypeid = get_fn_expr_argtype(fcinfo->flinfo, 0);
int typlen = get_typlen(argtypeid);
/* Lookup the datatype of the supplied argument */
Oid argtypeid = get_fn_expr_argtype(fcinfo->flinfo, 0);
if (typlen == 0)
{
/* Oid not in pg_type, should never happen. */
typlen = get_typlen(argtypeid);
if (typlen == 0) /* should not happen */
elog(ERROR, "cache lookup failed for type %u", argtypeid);
}
fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
sizeof(int));
*(int *)fcinfo->flinfo->fn_extra = typlen;
*((int *) fcinfo->flinfo->fn_extra) = typlen;
}
else
typlen = *((int *) fcinfo->flinfo->fn_extra);
if (*(int *)fcinfo->flinfo->fn_extra != -1)
PG_RETURN_INT32(*(int *)fcinfo->flinfo->fn_extra);
if (typlen == -1)
{
/* varlena type, possibly toasted */
result = toast_datum_size(value);
}
else if (typlen == -2)
{
/* cstring */
result = strlen(DatumGetCString(value)) + 1;
}
else
{
result = toast_datum_size(value) - VARHDRSZ;
PG_RETURN_INT32(result);
/* ordinary fixed-width type */
result = typlen;
}
PG_RETURN_INT32(result);
}