diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f33a16b7aa..8896988e5a 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1198,8 +1198,26 @@ include 'filename'
</para>
<para>
Note that when autovacuum runs, up to
- <xref linkend="guc-autovacuum-max-workers"> times this memory may be
- allocated, so be careful not to set the default value too high.
+ <xref linkend="guc-autovacuum-max-workers"> times this memory
+ may be allocated, so be careful not to set the default value
+ too high. It may be useful to control for this by separately
+ setting <xref linkend="guc-autovacuum-work-mem">.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry id="guc-autovacuum-work-mem" xreflabel="autovacuum_work_mem">
+ <term><varname>autovacuum_work_mem</varname> (<type>integer</type>)</term>
+ <indexterm>
+ <primary><varname>autovacuum_work_mem</> configuration parameter</primary>
+ </indexterm>
+ <listitem>
+ <para>
+ Specifies the maximum amount of memory to be used by each
+ autovacuum worker process. It defaults to -1, indicating that
+ the value of <xref linkend="guc-maintenance-work-mem"> should
+ be used instead. The setting has no effect on the behavior of
+ <command>VACUUM</command> when run in other contexts.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index d346772600..7b9837f4f4 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -10,13 +10,13 @@
* relations with finite memory space usage. To do that, we set upper bounds
* on the number of tuples and pages we will keep track of at once.
*
- * We are willing to use at most maintenance_work_mem memory space to keep
- * track of dead tuples. We initially allocate an array of TIDs of that size,
- * with an upper limit that depends on table size (this limit ensures we don't
- * allocate a huge area uselessly for vacuuming small tables). If the array
- * threatens to overflow, we suspend the heap scan phase and perform a pass of
- * index cleanup and page compaction, then resume the heap scan with an empty
- * TID array.
+ * We are willing to use at most maintenance_work_mem (or perhaps
+ * autovacuum_work_mem) memory space to keep track of dead tuples. We
+ * initially allocate an array of TIDs of that size, with an upper limit that
+ * depends on table size (this limit ensures we don't allocate a huge area
+ * uselessly for vacuuming small tables). If the array threatens to overflow,
+ * we suspend the heap scan phase and perform a pass of index cleanup and page
+ * compaction, then resume the heap scan with an empty TID array.
*
* If we're processing a table with no indexes, we can just vacuum each page
* as we go; there's no need to save up multiple tuples to minimize the number
@@ -1599,10 +1599,13 @@ static void
lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks)
{
long maxtuples;
+ int vac_work_mem = IsAutoVacuumWorkerProcess() &&
+ autovacuum_work_mem != -1 ?
+ autovacuum_work_mem : maintenance_work_mem;
if (vacrelstats->hasindex)
{
- maxtuples = (maintenance_work_mem * 1024L) / sizeof(ItemPointerData);
+ maxtuples = (vac_work_mem * 1024L) / sizeof(ItemPointerData);
maxtuples = Min(maxtuples, INT_MAX);
maxtuples = Min(maxtuples, MaxAllocSize / sizeof(ItemPointerData));
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 88ecd3834b..be370b19f9 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -110,6 +110,7 @@
*/
bool autovacuum_start_daemon = false;
int autovacuum_max_workers;
+int autovacuum_work_mem = -1;
int autovacuum_naptime;
int autovacuum_vac_thresh;
double autovacuum_vac_scale;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f3bf6e0aa2..e69e132f05 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -194,6 +194,7 @@ static const char *show_tcp_keepalives_count(void);
static bool check_maxconnections(int *newval, void **extra, GucSource source);
static bool check_max_worker_processes(int *newval, void **extra, GucSource source);
static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource source);
+static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource source);
static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
static void assign_effective_io_concurrency(int newval, void *extra);
static void assign_pgstat_temp_directory(const char *newval, void *extra);
@@ -2357,6 +2358,17 @@ static struct config_int ConfigureNamesInt[] =
check_autovacuum_max_workers, NULL, NULL
},
+ {
+ {"autovacuum_work_mem", PGC_SIGHUP, RESOURCES_MEM,
+ gettext_noop("Sets the maximum memory to be used by each autovacuum worker process."),
+ NULL,
+ GUC_UNIT_KB
+ },
+ &autovacuum_work_mem,
+ -1, -1, MAX_KILOBYTES,
+ check_autovacuum_work_mem, NULL, NULL
+ },
+
{
{"tcp_keepalives_idle", PGC_USERSET, CLIENT_CONN_OTHER,
gettext_noop("Time between issuing TCP keepalives."),
@@ -8777,6 +8789,29 @@ check_autovacuum_max_workers(int *newval, void **extra, GucSource source)
return true;
}
+static bool
+check_autovacuum_work_mem(int *newval, void **extra, GucSource source)
+{
+ /*
+ * -1 indicates fallback.
+ *
+ * If we haven't yet changed the boot_val default of -1, just let it be.
+ * Autovacuum will look to maintenance_work_mem instead.
+ */
+ if (*newval == -1)
+ return true;
+
+ /*
+ * We clamp manually-set values to at least 1MB. Since
+ * maintenance_work_mem is always set to at least this value, do the same
+ * here.
+ */
+ if (*newval < 1024)
+ *newval = 1024;
+
+ return true;
+}
+
static bool
check_max_worker_processes(int *newval, void **extra, GucSource source)
{
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6096fe4445..f8bdce34d3 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -124,6 +124,7 @@
# actively intend to use prepared transactions.
#work_mem = 1MB # min 64kB
#maintenance_work_mem = 16MB # min 1MB
+#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB # min 100kB
#dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
diff --git a/src/include/postmaster/autovacuum.h b/src/include/postmaster/autovacuum.h
index e96f07aaff..92560fe217 100644
--- a/src/include/postmaster/autovacuum.h
+++ b/src/include/postmaster/autovacuum.h
@@ -18,6 +18,7 @@
/* GUC variables */
extern bool autovacuum_start_daemon;
extern int autovacuum_max_workers;
+extern int autovacuum_work_mem;
extern int autovacuum_naptime;
extern int autovacuum_vac_thresh;
extern double autovacuum_vac_scale;