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Add pg_column_size() to return storage size of a column, including
possible compression. Mark Kirkwood
This commit is contained in:
Bruce Momjian
parent
b9cb132648
commit
a923602855
@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.262 2005/06/29 01:52:56 momjian Exp $
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$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.263 2005/07/06 19:02:52 momjian Exp $
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PostgreSQL documentation
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-->
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@ -2186,6 +2186,14 @@ PostgreSQL documentation
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<entry><literal>5</literal></entry>
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</row>
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<row>
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<entry><literal><function>pg_column_size</function>(<parameter>string</parameter>)</literal></entry>
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<entry><type>integer</type></entry>
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<entry>Number of bytes required to store the value, which might be compressed</entry>
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<entry><literal>pg_column_size('jo\\000se'::bytea)</literal></entry>
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<entry><literal>5</literal></entry>
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</row>
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<row>
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<entry><literal><function>position</function>(<parameter>substring</parameter> in <parameter>string</parameter>)</literal></entry>
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<entry><type>integer</type></entry>
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.49 2005/03/21 01:23:58 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.50 2005/07/06 19:02:52 momjian Exp $
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*
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*
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* INTERFACE ROUTINES
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@ -1436,3 +1436,45 @@ toast_fetch_datum_slice(varattrib *attr, int32 sliceoffset, int32 length)
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return result;
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}
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/* ----------
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* toast_datum_size
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*
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* Show the (possibly compressed) size of a datum
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* ----------
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*/
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Size
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toast_datum_size(Datum value)
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{
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varattrib *attr = (varattrib *) DatumGetPointer(value);
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Size result;
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if (VARATT_IS_EXTERNAL(attr))
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{
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/*
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* Attribute is stored externally - If it is compressed too,
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* then we need to get the external datum and calculate its size,
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* otherwise we just use the external rawsize.
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*/
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if (VARATT_IS_COMPRESSED(attr))
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{
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varattrib *attrext = toast_fetch_datum(attr);
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result = VARSIZE(attrext);
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pfree(attrext);
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}
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else
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result = attr->va_content.va_external.va_rawsize;
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}
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else
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{
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/*
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* Attribute is stored inline either compressed or not, just
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* calculate the size of the datum in either case.
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*/
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result = VARSIZE(attr);
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}
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return result;
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}
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.124 2005/07/04 18:56:44 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.125 2005/07/06 19:02:52 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -28,6 +28,7 @@
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/pg_locale.h"
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#include "utils/syscache.h"
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typedef struct varlena unknown;
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@ -2348,3 +2349,47 @@ md5_bytea(PG_FUNCTION_ARGS)
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result_text = PG_STR_GET_TEXT(hexsum);
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PG_RETURN_TEXT_P(result_text);
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}
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/*
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* Return the length of a datum, possibly compressed
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*/
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Datum
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pg_column_size(PG_FUNCTION_ARGS)
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{
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Datum value = PG_GETARG_DATUM(0);
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int result;
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/* fn_extra stores the fixed column length, or -1 for varlena. */
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if (fcinfo->flinfo->fn_extra == NULL) /* first call? */
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{
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/* On the first call lookup the datatype of the supplied argument */
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Oid argtypeid = get_fn_expr_argtype(fcinfo->flinfo, 0);
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HeapTuple tp;
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int typlen;
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tp = SearchSysCache(TYPEOID,
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ObjectIdGetDatum(argtypeid),
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0, 0, 0);
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if (!HeapTupleIsValid(tp))
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{
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/* Oid not in pg_type, should never happen. */
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ereport(ERROR,
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(errcode(ERRCODE_INTERNAL_ERROR),
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errmsg("invalid typid: %u", argtypeid)));
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}
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typlen = ((Form_pg_type)GETSTRUCT(tp))->typlen;
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ReleaseSysCache(tp);
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fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
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sizeof(int));
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*(int *)fcinfo->flinfo->fn_extra = typlen;
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}
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if (*(int *)fcinfo->flinfo->fn_extra != -1)
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PG_RETURN_INT32(*(int *)fcinfo->flinfo->fn_extra);
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else
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{
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result = toast_datum_size(value) - VARHDRSZ;
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PG_RETURN_INT32(result);
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}
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}
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@ -6,7 +6,7 @@
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*
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* Copyright (c) 2000-2005, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.22 2005/03/21 01:24:04 tgl Exp $
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* $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.23 2005/07/06 19:02:53 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -138,4 +138,12 @@ extern Datum toast_compress_datum(Datum value);
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*/
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extern Size toast_raw_datum_size(Datum value);
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/* ----------
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* toast_datum_size -
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*
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* Return the storage size of a varlena datum
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* ----------
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*/
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extern Size toast_datum_size(Datum value);
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#endif /* TUPTOASTER_H */
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.373 2005/07/01 19:19:03 tgl Exp $
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* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.374 2005/07/06 19:02:53 momjian Exp $
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*
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* NOTES
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* The script catalog/genbki.sh reads this file and generates .bki
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@ -3658,6 +3658,10 @@ DESCR("current value from last used sequence");
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DATA(insert OID = 2560 ( pg_postmaster_start_time PGNSP PGUID 12 f f t f s 0 1184 "" _null_ _null_ _null_ pgsql_postmaster_start_time - _null_ ));
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DESCR("postmaster start time");
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/* Column storage size */
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DATA(insert OID = 1269 ( pg_column_size PGNSP PGUID 12 f f t f i 1 23 "2276" _null_ _null_ _null_ pg_column_size - _null_ ));
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DESCR("bytes required to store the value, perhaps with compression");
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/* new functions for Y-direction rtree opclasses */
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DATA(insert OID = 2562 ( box_below PGNSP PGUID 12 f f t f i 2 16 "603 603" _null_ _null_ _null_ box_below - _null_ ));
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DESCR("is below");
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.258 2005/06/17 22:32:50 tgl Exp $
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* $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.259 2005/07/06 19:02:54 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -601,6 +601,7 @@ extern Datum byteacat(PG_FUNCTION_ARGS);
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extern Datum byteapos(PG_FUNCTION_ARGS);
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extern Datum bytea_substr(PG_FUNCTION_ARGS);
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extern Datum bytea_substr_no_len(PG_FUNCTION_ARGS);
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extern Datum pg_column_size(PG_FUNCTION_ARGS);
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/* version.c */
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extern Datum pgsql_version(PG_FUNCTION_ARGS);
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