After someone in IRC asked if there was an equivalent to MySQL's server_id, it was noted that we do have a system identifier but it's not very accessible.
The attached patch implements a pg_system_identifier() function that exposes it. Shall I add this to the next commitfest? -- Vik
*** a/doc/src/sgml/func.sgml --- b/doc/src/sgml/func.sgml *************** *** 13473,13478 **** SELECT * FROM pg_ls_dir('.') WITH ORDINALITY AS t(ls,n); --- 13473,13484 ---- </row> <row> + <entry><literal><function>pg_system_identifier()</function></literal></entry> + <entry><type>text</type></entry> + <entry>system identifier for the database cluster</entry> + </row> + + <row> <entry><literal><function>pg_trigger_depth()</function></literal></entry> <entry><type>int</type></entry> <entry>current nesting level of <productname>PostgreSQL</> triggers *** a/src/backend/access/transam/xlogfuncs.c --- b/src/backend/access/transam/xlogfuncs.c *************** *** 35,40 **** --- 35,50 ---- static void validate_xlog_location(char *str); + /* + * pg_system_identifier + */ + Datum + pg_system_identifier(PG_FUNCTION_ARGS) + { + char ret[32]; + sprintf(ret, UINT64_FORMAT, GetSystemIdentifier()); + PG_RETURN_TEXT_P(cstring_to_text(ret)); + } /* * pg_start_backup: set up for taking an on-line backup dump *** a/src/include/access/xlog_fn.h --- b/src/include/access/xlog_fn.h *************** *** 13,18 **** --- 13,19 ---- #include "fmgr.h" + extern Datum pg_system_identifier(PG_FUNCTION_ARGS); extern Datum pg_start_backup(PG_FUNCTION_ARGS); extern Datum pg_stop_backup(PG_FUNCTION_ARGS); extern Datum pg_switch_xlog(PG_FUNCTION_ARGS); *** a/src/include/catalog/catversion.h --- b/src/include/catalog/catversion.h *************** *** 53,58 **** --- 53,59 ---- */ /* yyyymmddN */ + /* needs bump */ #define CATALOG_VERSION_NO 201307221 #endif *** a/src/include/catalog/pg_proc.h --- b/src/include/catalog/pg_proc.h *************** *** 2954,2959 **** DATA(insert OID = 2171 ( pg_cancel_backend PGNSP PGUID 12 1 0 0 0 f f f f t f v --- 2954,2961 ---- DESCR("cancel a server process' current query"); DATA(insert OID = 2096 ( pg_terminate_backend PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 16 "23" _null_ _null_ _null_ _null_ pg_terminate_backend _null_ _null_ _null_ )); DESCR("terminate a server process"); + DATA(insert OID = 3179 ( pg_system_identifier PGNSP PGUID 12 1 0 0 0 f f f f f f i 0 0 25 "" _null_ _null_ _null_ _null_ pg_system_identifier _null_ _null_ _null_ )); + DESCR("database system identifier"); DATA(insert OID = 2172 ( pg_start_backup PGNSP PGUID 12 1 0 0 0 f f f f t f v 2 0 25 "25 16" _null_ _null_ _null_ _null_ pg_start_backup _null_ _null_ _null_ )); DESCR("prepare for taking an online backup"); DATA(insert OID = 2173 ( pg_stop_backup PGNSP PGUID 12 1 0 0 0 f f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_stop_backup _null_ _null_ _null_ ));
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