On Wed, Sep 3, 2014 at 05:17:17PM -0400, Robert Haas wrote: > > I had a look at this and came upon a problem --- there is no multi-xid > > SQL data type, and in fact the system catalogs that store mxid values > > use xid, e.g.: > > > > relminmxid | xid | not null > > > > With no mxid data type, there is no way to do function overloading to > > cause age to call the mxid variant. > > > > Should we use an explicit mxid_age() function name? Add an mxid data > > type? > > Maybe both. But mxid_age() is probably the simpler way forward just to start.
OK, patch applied using mxid_age() and no new data type. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. +
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml new file mode 100644 index cf174f0..d692308 *** a/doc/src/sgml/maintenance.sgml --- b/doc/src/sgml/maintenance.sgml *************** HINT: Stop the postmaster and vacuum th *** 640,646 **** possible multixact ID still appearing in any tuple of that table. If this value is older than <xref linkend="guc-vacuum-multixact-freeze-table-age">, a whole-table ! scan is forced. Whole-table <command>VACUUM</> scans, regardless of what causes them, enable advancing the value for that table. Eventually, as all tables in all databases are scanned and their oldest multixact values are advanced, on-disk storage for older --- 640,651 ---- possible multixact ID still appearing in any tuple of that table. If this value is older than <xref linkend="guc-vacuum-multixact-freeze-table-age">, a whole-table ! scan is forced. <function>mxid_age()</> can be used on ! <structname>pg_class</>.<structfield>relminmxid</> to find its age. ! </para> ! ! <para> ! Whole-table <command>VACUUM</> scans, regardless of what causes them, enable advancing the value for that table. Eventually, as all tables in all databases are scanned and their oldest multixact values are advanced, on-disk storage for older diff --git a/src/backend/utils/adt/xid.c b/src/backend/utils/adt/xid.c new file mode 100644 index 602a9e5..ecb3cf5 *** a/src/backend/utils/adt/xid.c --- b/src/backend/utils/adt/xid.c *************** *** 16,21 **** --- 16,22 ---- #include <limits.h> + #include "access/multixact.h" #include "access/transam.h" #include "access/xact.h" #include "libpq/pqformat.h" *************** xid_age(PG_FUNCTION_ARGS) *** 100,105 **** --- 101,121 ---- PG_RETURN_INT32(INT_MAX); PG_RETURN_INT32((int32) (now - xid)); + } + + /* + * mxid_age - compute age of a multi XID (relative to latest stable mxid) + */ + Datum + mxid_age(PG_FUNCTION_ARGS) + { + TransactionId xid = PG_GETARG_TRANSACTIONID(0); + MultiXactId now = ReadNextMultiXactId(); + + if (!MultiXactIdIsValid(xid)) + PG_RETURN_INT32(INT_MAX); + + PG_RETURN_INT32((int32) (now - xid)); } /* diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h new file mode 100644 index e1b62a5..e0875b7 *** a/src/include/catalog/catversion.h --- b/src/include/catalog/catversion.h *************** *** 53,58 **** */ /* yyyymmddN */ ! #define CATALOG_VERSION_NO 201408281 #endif --- 53,58 ---- */ /* yyyymmddN */ ! #define CATALOG_VERSION_NO 201409021 #endif diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h new file mode 100644 index 5176ed0..09e138b *** a/src/include/catalog/pg_proc.h --- b/src/include/catalog/pg_proc.h *************** DATA(insert OID = 1180 ( abstime PG *** 1277,1282 **** --- 1277,1284 ---- DESCR("convert timestamp with time zone to abstime"); DATA(insert OID = 1181 ( age PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 23 "28" _null_ _null_ _null_ _null_ xid_age _null_ _null_ _null_ )); DESCR("age of a transaction ID, in transactions before current transaction"); + DATA(insert OID = 3218 ( mxid_age PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 23 "28" _null_ _null_ _null_ _null_ mxid_age _null_ _null_ _null_ )); + DESCR("age of a multi-transaction ID, in multi-transactions before current multi-transaction"); DATA(insert OID = 1188 ( timestamptz_mi PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1186 "1184 1184" _null_ _null_ _null_ _null_ timestamp_mi _null_ _null_ _null_ )); DATA(insert OID = 1189 ( timestamptz_pl_interval PGNSP PGUID 12 1 0 0 0 f f f f t f s 2 0 1184 "1184 1186" _null_ _null_ _null_ _null_ timestamptz_pl_interval _null_ _null_ _null_ )); diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h new file mode 100644 index 78cc0a0..d88e7a3 *** a/src/include/utils/builtins.h --- b/src/include/utils/builtins.h *************** extern Datum xidrecv(PG_FUNCTION_ARGS); *** 845,850 **** --- 845,851 ---- extern Datum xidsend(PG_FUNCTION_ARGS); extern Datum xideq(PG_FUNCTION_ARGS); extern Datum xid_age(PG_FUNCTION_ARGS); + extern Datum mxid_age(PG_FUNCTION_ARGS); extern int xidComparator(const void *arg1, const void *arg2); extern Datum cidin(PG_FUNCTION_ARGS); extern Datum cidout(PG_FUNCTION_ARGS);
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