--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * checkfiles.c
+ * support to clean up stale relation files on crash recovery
+ *
+ * If a backend crashes while in a transaction that has created or
+ * deleted a relfilenode, a stale file can be left over in the data
+ * directory. This file contains routines to clean up those stale
+ * files on recovery.
+ *
+ * This adds a 17% increase in startup cost for 100 empty databases. bjm
+ * One optimization would be to create a 'dirty' file on a postmaster recovery
+ * and remove the dirty flag only when a clean startup detects no unreferenced
+ * files, and use the 'dirty' flag to determine if we should run this on
+ * a clean startup.
+ *
+ * $PostgreSQL$
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "storage/fd.h"
+
+#include "utils/flatfiles.h"
+#include "miscadmin.h"
+#include "catalog/pg_tablespace.h"
+#include "catalog/catalog.h"
+#include "access/skey.h"
+#include "utils/fmgroids.h"
+#include "access/relscan.h"
+#include "access/heapam.h"
+#include "utils/resowner.h"
+
+static void CheckStaleRelFilesFrom(Oid tablespaceoid, Oid dboid);
+static void CheckStaleRelFilesFromTablespace(Oid tablespaceoid);
+
+/* Like AllocateDir, but ereports on failure */
+static DIR *
+AllocateDirChecked(char *path)
+{
+ DIR *dirdesc = AllocateDir(path);
+
+ if (dirdesc == NULL)
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not open directory \"%s\": %m",
+ path)));
+ return dirdesc;
+}
+
+/*
+ * Scan through all tablespaces for relations left over
+ * by aborted transactions.
+ *
+ * For example, if a transaction issues
+ * BEGIN; CREATE TABLE foobar ();
+ * and then the backend crashes, the file is left in the
+ * tablespace until CheckStaleRelFiles deletes it.
+ */
+void
+CheckStaleRelFiles(void)
+{
+ DIR *dirdesc;
+ struct dirent *de;
+ char *path;
+ int pathlen;
+
+ pathlen = strlen(DataDir) + 11 + 1;
+ path = (char *) palloc(pathlen);
+ snprintf(path, pathlen, "%s/pg_tblspc/", DataDir);
+ dirdesc = AllocateDirChecked(path);
+ while ((de = readdir(dirdesc)) != NULL)
+ {
+ char *invalid;
+ Oid tablespaceoid;
+
+ /* Check that the directory name looks like valid tablespace link. */
+ tablespaceoid = (Oid) strtol(de->d_name, &invalid, 10);
+ if (invalid[0] == '\0')
+ CheckStaleRelFilesFromTablespace(tablespaceoid);
+ }
+ FreeDir(dirdesc);
+ pfree(path);
+
+ CheckStaleRelFilesFromTablespace(DEFAULTTABLESPACE_OID);
+}
+
+/* Scan a specific tablespace for stale relations */
+static void
+CheckStaleRelFilesFromTablespace(Oid tablespaceoid)
+{
+ DIR *dirdesc;
+ struct dirent *de;
+ char *path;
+
+ path = GetTablespacePath(tablespaceoid);
+
+ dirdesc = AllocateDirChecked(path);
+ while ((de = readdir(dirdesc)) != NULL)
+ {
+ char *invalid;
+ Oid dboid;
+
+ dboid = (Oid) strtol(de->d_name, &invalid, 10);
+ if (invalid[0] == '\0')
+ CheckStaleRelFilesFrom(tablespaceoid, dboid);
+ }
+ FreeDir(dirdesc);
+ pfree(path);
+}
+
+/* Scan a specific database in a specific tablespace for stale relations.
+ *
+ * First, pg_class for the database is opened, and the relfilenodes of all
+ * relations mentioned there are stored in a hash table.
+ *
+ * Then the directory is scanned. Every file in the directory that's not
+ * found in pg_class (the hash table) is logged.
+ */
+static void
+CheckStaleRelFilesFrom(Oid tablespaceoid, Oid dboid)
+{
+ DIR *dirdesc;
+ struct dirent *de;
+ HASHCTL hashctl;
+ HTAB *relfilenodeHash;
+ MemoryContext mcxt;
+ RelFileNode rnode;
+ char *path;
+
+ /*
+ * We create a private memory context so that we can easily deallocate the
+ * hash table and its contents
+ */
+ mcxt = AllocSetContextCreate(TopMemoryContext, "CheckStaleRelFiles",
+ ALLOCSET_DEFAULT_MINSIZE,
+ ALLOCSET_DEFAULT_INITSIZE,
+ ALLOCSET_DEFAULT_MAXSIZE);
+
+ hashctl.hash = tag_hash;
+
+ /*
+ * The entry contents is not used for anything, we just check if an oid is
+ * in the hash table or not.
+ */
+ hashctl.keysize = sizeof(Oid);
+ hashctl.entrysize = 1;
+ hashctl.hcxt = mcxt;
+ relfilenodeHash = hash_create("relfilenodeHash", 100, &hashctl,
+ HASH_FUNCTION
+ | HASH_ELEM | HASH_CONTEXT);
+
+ /* Read all relfilenodes from pg_class into the hash table */
+ {
+ ResourceOwner owner,
+ oldowner;
+ Relation rel;
+ HeapScanDesc scan;
+ HeapTuple tuple;
+
+ /* Need a resowner to keep the heapam and buffer code happy */
+ owner = ResourceOwnerCreate(NULL, "CheckStaleRelFiles");
+ oldowner = CurrentResourceOwner;
+ CurrentResourceOwner = owner;
+
+ rnode.spcNode = tablespaceoid;
+ rnode.dbNode = dboid;
+ rnode.relNode = RelationRelationId;
+ rel = XLogOpenRelation(true, 0, rnode);
+
+ scan = heap_beginscan(rel, SnapshotNow, 0, NULL);
+ while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
+ {
+ Form_pg_class classform = (Form_pg_class) GETSTRUCT(tuple);
+
+ hash_search(relfilenodeHash, &classform->relfilenode,
+ HASH_ENTER, NULL);
+ }
+ heap_endscan(scan);
+
+ XLogCloseRelation(rnode);
+ CurrentResourceOwner = oldowner;
+ ResourceOwnerDelete(owner);
+ }
+
+ /* Scan the directory */
+ path = GetDatabasePath(dboid, tablespaceoid);
+
+ dirdesc = AllocateDirChecked(path);
+ while ((de = readdir(dirdesc)) != NULL)
+ {
+ char *invalid;
+ Oid relfilenode;
+
+ relfilenode = strtol(de->d_name, &invalid, 10);
+ if (invalid[0] == '\0')
+ {
+ /*
+ * Filename was a valid number, check if pg_class knows about it
+ */
+ if (hash_search(relfilenodeHash, &relfilenode,
+ HASH_FIND, NULL) == NULL)
+ {
+ char *filepath;
+
+ rnode.spcNode = tablespaceoid;
+ rnode.dbNode = dboid;
+ rnode.relNode = relfilenode;
+
+ filepath = relpath(rnode);
+
+ ereport(LOG,
+ (errcode_for_file_access(),
+ errmsg("The table or index file \"%s\" is stale and can be safely removed",
+ filepath)));
+ pfree(filepath);
+ }
+ }
+ }
+ FreeDir(dirdesc);
+ pfree(path);
+ hash_destroy(relfilenodeHash);
+ MemoryContextDelete(mcxt);
+}
projects / users / bernd / postgres.git / commitdiff