mirror of https://github.com/postgres/postgres
Thomas G. Lockhart
28 years ago
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/*-------------------------------------------------------------------------
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* |
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* database.c-- |
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* miscellanious initialization support stuff |
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* |
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* Copyright (c) 1994, Regents of the University of California |
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* |
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* |
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* IDENTIFICATION |
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* $Header: /cvsroot/pgsql/src/backend/utils/misc/Attic/database.c,v 1.1 1997/11/07 07:05:46 thomas Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#include <string.h> |
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#include <stdlib.h> |
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#include <stdio.h> |
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#include <unistd.h> |
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#include <fcntl.h> |
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#include "postgres.h" |
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#include "miscadmin.h" |
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#include "utils/elog.h" |
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#include "utils/builtins.h" |
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#include "utils/syscache.h" |
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#include "access/heapam.h" |
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#include "storage/bufmgr.h" |
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#include "catalog/catname.h" |
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#include "catalog/pg_proc.h" |
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#include "catalog/pg_database.h" |
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#include "access/xact.h" |
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#include "storage/bufpage.h" |
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/* GetDatabaseInfo()
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* Pull database information from pg_database. |
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*/ |
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int |
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GetDatabaseInfo(char *name, Oid *owner, char *path) |
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{ |
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Oid dbowner, |
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dbid; |
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char dbpath[MAXPGPATH+1]; |
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text *dbtext; |
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Relation dbrel; |
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HeapTuple dbtup; |
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HeapTuple tup; |
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Buffer buf; |
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HeapScanDesc scan; |
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ScanKeyData scanKey; |
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dbrel = heap_openr(DatabaseRelationName); |
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if (!RelationIsValid(dbrel)) |
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elog(FATAL,"GetDatabaseInfo: cannot open relation \"%-.*s\"", |
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DatabaseRelationName); |
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ScanKeyEntryInitialize(&scanKey, 0, Anum_pg_database_datname, |
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NameEqualRegProcedure, NameGetDatum(name)); |
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scan = heap_beginscan(dbrel, 0, NowTimeQual, 1, &scanKey); |
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if (!HeapScanIsValid(scan)) |
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elog(WARN, "GetDatabaseInfo: cannot begin scan of %s", DatabaseRelationName); |
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/*
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* Since we're going to close the relation, copy the tuple. |
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*/ |
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tup = heap_getnext(scan, 0, &buf); |
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if (HeapTupleIsValid(tup)) |
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{ |
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dbtup = heap_copytuple(tup); |
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ReleaseBuffer(buf); |
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} |
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else |
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dbtup = tup; |
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heap_endscan(scan); |
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if (!HeapTupleIsValid(dbtup)) |
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{ |
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elog(NOTICE,"GetDatabaseInfo: %s entry not found %s", |
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DatabaseRelationName,name); |
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return TRUE; |
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} |
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dbowner = (Oid) heap_getattr(dbtup, InvalidBuffer, |
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Anum_pg_database_datdba, |
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RelationGetTupleDescriptor(dbrel), |
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(char *) NULL); |
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dbid = dbtup->t_oid; |
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dbtext = (text *) heap_getattr(dbtup, InvalidBuffer, |
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Anum_pg_database_datpath, |
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RelationGetTupleDescriptor(dbrel), |
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(char *) NULL); |
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memcpy(dbpath, VARDATA(dbtext), (VARSIZE(dbtext)-VARHDRSZ)); |
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*(dbpath+(VARSIZE(dbtext)-VARHDRSZ)) = '\0'; |
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heap_close(dbrel); |
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owner = palloc(sizeof(Oid)); |
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*owner = dbowner; |
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path = palloc(strlen(dbpath)+1); |
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strcpy(path, dbpath); |
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return FALSE; |
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} /* GetDatabaseInfo() */ |
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char * |
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ExpandDatabasePath(char *dbpath) |
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{ |
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char *path; |
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char *cp; |
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char buf[MAXPGPATH+1]; |
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/* leading path delimiter? then already absolute path */ |
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if (*dbpath == SEP_CHAR) |
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{ |
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cp = strrchr(dbpath, SEP_CHAR); |
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strncpy(buf,dbpath,(cp-dbpath)); |
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sprintf(&buf[cp-dbpath], "%cbase%c%s", SEP_CHAR, SEP_CHAR, (cp+1)); |
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} |
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/* path delimiter somewhere? then has leading environment variable */ |
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else if (strchr(dbpath, SEP_CHAR) != NULL) |
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{ |
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cp = strchr(dbpath, SEP_CHAR); |
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strncpy(buf,dbpath,(cp-dbpath)); |
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buf[cp-dbpath] = '\0'; |
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path = getenv(buf); |
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sprintf(buf, "%s%cbase%c%s", path, SEP_CHAR, SEP_CHAR, (cp+1)); |
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} |
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/* no path delimiter? then add the default path prefixes */ |
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else |
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{ |
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sprintf(buf, "%s%cbase%c%s", DataDir, SEP_CHAR, SEP_CHAR, dbpath); |
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} |
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path = palloc(strlen(buf)+1); |
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strcpy(path,buf); |
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return path; |
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} /* ExpandDatabasePath() */ |
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/* --------------------------------
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* GetRawDatabaseInfo() -- Find the OID and path of the database. |
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* |
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* The database's oid forms half of the unique key for the system |
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* caches and lock tables. We therefore want it initialized before |
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* we open any relations, since opening relations puts things in the |
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* cache. To get around this problem, this code opens and scans the |
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* pg_database relation by hand. |
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* |
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* This algorithm relies on the fact that first attribute in the |
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* pg_database relation schema is the database name. It also knows |
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* about the internal format of tuples on disk and the length of |
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* the datname attribute. It knows the location of the pg_database |
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* file. |
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* Actually, the code looks as though it is using the pg_database |
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* tuple definition to locate the database name, so the above statement |
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* seems to be no longer correct. - thomas 1997-11-01 |
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* |
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* This code is called from InitPostgres(), before we chdir() to the |
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* local database directory and before we open any relations. |
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* Used to be called after the chdir(), but we now want to confirm |
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* the location of the target database using pg_database info. |
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* - thomas 1997-11-01 |
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* -------------------------------- |
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*/ |
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void |
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GetRawDatabaseInfo(char *name, Oid *owner, Oid *db_id, char *path) |
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{ |
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int dbfd; |
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int fileflags; |
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int nbytes; |
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int max, |
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i; |
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HeapTuple tup; |
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Page pg; |
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PageHeader ph; |
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char *dbfname; |
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Form_pg_database tup_db; |
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dbfname = (char *) palloc(strlen(DataDir) + strlen("pg_database") + 2); |
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sprintf(dbfname, "%s%cpg_database", DataDir, SEP_CHAR); |
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fileflags = O_RDONLY; |
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if ((dbfd = open(dbfname, O_RDONLY, 0)) < 0) |
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elog(FATAL, "Cannot open %s", dbfname); |
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pfree(dbfname); |
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/* ----------------
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* read and examine every page in pg_database |
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* |
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* Raw I/O! Read those tuples the hard way! Yow! |
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* |
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* Why don't we use the access methods or move this code |
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* someplace else? This is really pg_database schema dependent |
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* code. Perhaps it should go in lib/catalog/pg_database? |
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* -cim 10/3/90 |
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* |
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* mao replies 4 apr 91: yeah, maybe this should be moved to |
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* lib/catalog. however, we CANNOT use the access methods since |
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* those use the buffer cache, which uses the relation cache, which |
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* requires that the dbid be set, which is what we're trying to do |
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* here. |
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* ---------------- |
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*/ |
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pg = (Page) palloc(BLCKSZ); |
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ph = (PageHeader) pg; |
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while ((nbytes = read(dbfd, pg, BLCKSZ)) == BLCKSZ) |
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{ |
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max = PageGetMaxOffsetNumber(pg); |
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/* look at each tuple on the page */ |
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for (i = 0; i <= max; i++) |
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{ |
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int offset; |
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/* if it's a freed tuple, ignore it */ |
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if (!(ph->pd_linp[i].lp_flags & LP_USED)) |
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continue; |
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/* get a pointer to the tuple itself */ |
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offset = (int) ph->pd_linp[i].lp_off; |
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tup = (HeapTuple) (((char *) pg) + offset); |
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/*
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* if the tuple has been deleted (the database was destroyed), |
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* skip this tuple. XXX warning, will robinson: violation of |
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* transaction semantics happens right here. we should check |
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* to be sure that the xact that deleted this tuple actually |
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* committed. only way to do this at init time is to paw over |
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* the log relation by hand, too. let's be optimistic. |
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* |
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* XXX This is an evil type cast. tup->t_xmax is char[5] while |
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* TransactionId is struct * { char data[5] }. It works but |
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* if data is ever moved and no longer the first field this |
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* will be broken!! -mer 11 Nov 1991. |
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*/ |
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if (TransactionIdIsValid((TransactionId) tup->t_xmax)) |
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continue; |
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/*
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* Okay, see if this is the one we want. XXX 1 july 91: mao |
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* and mer discover that tuples now squash t_bits. Why is |
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* this? |
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* |
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* 24 july 92: mer realizes that the t_bits field is only used |
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* in the event of null values. If no fields are null we |
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* reduce the header size by doing the squash. t_hoff tells |
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* you exactly how big the header actually is. use the PC |
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* means of getting at sys cat attrs. |
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*/ |
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tup_db = (Form_pg_database) GETSTRUCT(tup); |
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if (strncmp(name, |
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&(tup_db->datname.data[0]), |
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16) == 0) |
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{ |
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*db_id = tup->t_oid; |
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strncpy(path, VARDATA(&(tup_db->datpath)), |
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(VARSIZE(&(tup_db->datpath))-VARHDRSZ)); |
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*(path+VARSIZE(&(tup_db->datpath))-VARHDRSZ) = '\0'; |
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goto done; |
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} |
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} |
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} |
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done: |
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close(dbfd); |
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pfree(pg); |
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} /* GetRawDatabaseInfo() */ |
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