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Make pg_relation_size() and friends return NULL if the object doesn't exist.

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That avoids errors when the functions are used in queries like "SELECT
pg_relation_size(oid) FROM pg_class", and a table is dropped concurrently.

Phil Sorber
This commit is contained in:
Heikki Linnakangas 2012-01-19 13:06:30 +02:00
parent 6f6b46c9c0
commit fa352d662e
2 changed files with 89 additions and 35 deletions
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5
doc/src/sgml/func.sgml
View File

@ -14979,6 +14979,11 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
the table name.
</para>
<para>
If an OID that does not represent an existing object is passed as
argument to one of the above functions, NULL is returned.
</para>
<para>
The functions shown in <xref linkend="functions-admin-dblocation"> assist
in identifying the specific disk files associated with database objects.

119
src/backend/utils/adt/dbsize.c
View File

@ -120,12 +120,6 @@ calculate_database_size(Oid dbOid)
FreeDir(dirdesc);
/* Complain if we found no trace of the DB at all */
if (!totalsize)
ereport(ERROR,
(ERRCODE_UNDEFINED_DATABASE,
errmsg("database with OID %u does not exist", dbOid)));
return totalsize;
}
@ -133,8 +127,14 @@ Datum
pg_database_size_oid(PG_FUNCTION_ARGS)
{
Oid dbOid = PG_GETARG_OID(0);
int64 size;
PG_RETURN_INT64(calculate_database_size(dbOid));
size = calculate_database_size(dbOid);
if (size == 0)
PG_RETURN_NULL();
PG_RETURN_INT64(size);
}
Datum
@ -142,13 +142,20 @@ pg_database_size_name(PG_FUNCTION_ARGS)
{
Name dbName = PG_GETARG_NAME(0);
Oid dbOid = get_database_oid(NameStr(*dbName), false);
int64 size;
PG_RETURN_INT64(calculate_database_size(dbOid));
size = calculate_database_size(dbOid);
if (size == 0)
PG_RETURN_NULL();
PG_RETURN_INT64(size);
}
/*
* calculate total size of tablespace
* Calculate total size of tablespace. Returns -1 if the tablespace directory
* cannot be found.
*/
static int64
calculate_tablespace_size(Oid tblspcOid)
@ -184,10 +191,7 @@ calculate_tablespace_size(Oid tblspcOid)
dirdesc = AllocateDir(tblspcPath);
if (!dirdesc)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open tablespace directory \"%s\": %m",
tblspcPath)));
return -1;
while ((direntry = ReadDir(dirdesc, tblspcPath)) != NULL)
{
@ -226,8 +230,14 @@ Datum
pg_tablespace_size_oid(PG_FUNCTION_ARGS)
{
Oid tblspcOid = PG_GETARG_OID(0);
int64 size;
PG_RETURN_INT64(calculate_tablespace_size(tblspcOid));
size = calculate_tablespace_size(tblspcOid);
if (size < 0)
PG_RETURN_NULL();
PG_RETURN_INT64(size);
}
Datum
@ -235,8 +245,14 @@ pg_tablespace_size_name(PG_FUNCTION_ARGS)
{
Name tblspcName = PG_GETARG_NAME(0);
Oid tblspcOid = get_tablespace_oid(NameStr(*tblspcName), false);
int64 size;
PG_RETURN_INT64(calculate_tablespace_size(tblspcOid));
size = calculate_tablespace_size(tblspcOid);
if (size < 0)
PG_RETURN_NULL();
PG_RETURN_INT64(size);
}
@ -289,7 +305,17 @@ pg_relation_size(PG_FUNCTION_ARGS)
Relation rel;
int64 size;
rel = relation_open(relOid, AccessShareLock);
rel = try_relation_open(relOid, AccessShareLock);
/*
* Before 9.2, we used to throw an error if the relation didn't exist, but
* that makes queries like "SELECT pg_relation_size(oid) FROM pg_class"
* less robust, because while we scan pg_class with an MVCC snapshot,
* someone else might drop the table. It's better to return NULL for
* alread-dropped tables than throw an error and abort the whole query.
*/
if (rel == NULL)
PG_RETURN_NULL();
size = calculate_relation_size(&(rel->rd_node), rel->rd_backend,
forkname_to_number(text_to_cstring(forkName)));
@ -339,14 +365,11 @@ calculate_toast_table_size(Oid toastrelid)
* those won't have attached toast tables, but they can have multiple forks.
*/
static int64
calculate_table_size(Oid relOid)
calculate_table_size(Relation rel)
{
int64 size = 0;
Relation rel;
ForkNumber forkNum;
rel = relation_open(relOid, AccessShareLock);
/*
* heap size, including FSM and VM
*/
@ -360,8 +383,6 @@ calculate_table_size(Oid relOid)
if (OidIsValid(rel->rd_rel->reltoastrelid))
size += calculate_toast_table_size(rel->rd_rel->reltoastrelid);
relation_close(rel, AccessShareLock);
return size;
}
@ -371,12 +392,9 @@ calculate_table_size(Oid relOid)
* Can be applied safely to an index, but you'll just get zero.
*/
static int64
calculate_indexes_size(Oid relOid)
calculate_indexes_size(Relation rel)
{
int64 size = 0;
Relation rel;
rel = relation_open(relOid, AccessShareLock);
/*
* Aggregate all indexes on the given relation
@ -405,8 +423,6 @@ calculate_indexes_size(Oid relOid)
list_free(index_oids);
}
relation_close(rel, AccessShareLock);
return size;
}
@ -414,16 +430,38 @@ Datum
pg_table_size(PG_FUNCTION_ARGS)
{
Oid relOid = PG_GETARG_OID(0);
Relation rel;
int64 size;
PG_RETURN_INT64(calculate_table_size(relOid));
rel = try_relation_open(relOid, AccessShareLock);
if (rel == NULL)
PG_RETURN_NULL();
size = calculate_table_size(rel);
relation_close(rel, AccessShareLock);
PG_RETURN_INT64(size);
}
Datum
pg_indexes_size(PG_FUNCTION_ARGS)
{
Oid relOid = PG_GETARG_OID(0);
Relation rel;
int64 size;
PG_RETURN_INT64(calculate_indexes_size(relOid));
rel = try_relation_open(relOid, AccessShareLock);
if (rel == NULL)
PG_RETURN_NULL();
size = calculate_indexes_size(rel);
relation_close(rel, AccessShareLock);
PG_RETURN_INT64(size);
}
/*
@ -431,7 +469,7 @@ pg_indexes_size(PG_FUNCTION_ARGS)
* including heap data, index data, toast data, FSM, VM.
*/
static int64
calculate_total_relation_size(Oid Relid)
calculate_total_relation_size(Relation rel)
{
int64 size;
@ -439,12 +477,12 @@ calculate_total_relation_size(Oid Relid)
* Aggregate the table size, this includes size of the heap, toast and
* toast index with free space and visibility map
*/
size = calculate_table_size(Relid);
size = calculate_table_size(rel);
/*
* Add size of all attached indexes as well
*/
size += calculate_indexes_size(Relid);
size += calculate_indexes_size(rel);
return size;
}
@ -452,9 +490,20 @@ calculate_total_relation_size(Oid Relid)
Datum
pg_total_relation_size(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
Oid relOid = PG_GETARG_OID(0);
Relation rel;
int64 size;
PG_RETURN_INT64(calculate_total_relation_size(relid));
rel = try_relation_open(relOid, AccessShareLock);
if (rel == NULL)
PG_RETURN_NULL();
size = calculate_total_relation_size(rel);
relation_close(rel, AccessShareLock);
PG_RETURN_INT64(size);
}
/*