On Sat, Mar 7, 2020 at 9:07 AM Tom Lane <t...@sss.pgh.pa.us> wrote:
> Tomas Vondra <tomas.von...@2ndquadrant.com> writes:
> > So I think we should either rename e_i_c or keep it as is, and then also
> > have a new GUC. And then translate the values between those (but that
> > might be overkill).
>
> Please DON'T try to have two interrelated GUCs for this. We learned
> our lesson about that years ago.
Ack.
> I think dropping the existing GUC is a perfectly sane thing to do,
> if the new definition wouldn't be compatible. In practice few
> people will notice, because few will have set it.
That's what I thought too, but if Andres is right that "it's not like
anybody knew how to infer a useful value", I'm wondering it's enough
if we just provide an explanation of the change in the release notes.
The default doesn't change (1 goes to 1), so most people will
experience no change, but it you had it set to (say) 42 after careful
experimentation, you might like to consider updating it to the result
of:
select round(sum(42 / n::float)) as new_setting from
generate_series(1, 42) s(n)
Here's a patch set to remove the spindle stuff, add a maintenance
variant, and use the maintenance one in
heap_compute_xid_horizon_for_tuples().
From fc472c5b473e3495e92ec9cf021b6e6393579ca5 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.mu...@gmail.com>
Date: Sat, 7 Mar 2020 15:04:34 +1300
Subject: [PATCH 1/2] Simplify the effective_io_concurrency setting.
The effective_io_concurrency GUC and tablespace option were previously not used
directly to control the number of prefetches we'd issue. Instead, they were
passed through a formula based on a theory about RAID spindles and
probabilities. Today, a lot of people are familiar with the concept of I/O
request queues and have never seen a spinning disk, so let's switch to
something a little easier to justify.
If users were using a setting higher than the default value 1, then they will
need to increase the value for the same effect. The query to compute the new
setting corresponding to the old setting OLD is:
select round(sum(OLD / n::float)) as new_setting
from generate_series(1, OLD) s(n);
Discussion: https://postgr.es/m/CA%2BhUKGJUw08dPs_3EUcdO6M90GnjofPYrWp4YSLaBkgYwS-AqA%40mail.gmail.com
---
src/backend/executor/nodeBitmapHeapscan.c | 18 +-----
src/backend/storage/buffer/bufmgr.c | 74 +++--------------------
src/backend/utils/misc/guc.c | 29 +--------
src/include/storage/bufmgr.h | 1 -
4 files changed, 13 insertions(+), 109 deletions(-)
diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index ae8a11da30..726d3a2d9a 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -707,7 +707,6 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
{
BitmapHeapScanState *scanstate;
Relation currentRelation;
- int io_concurrency;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
@@ -737,8 +736,6 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
scanstate->prefetch_iterator = NULL;
scanstate->prefetch_pages = 0;
scanstate->prefetch_target = 0;
- /* may be updated below */
- scanstate->prefetch_maximum = target_prefetch_pages;
scanstate->pscan_len = 0;
scanstate->initialized = false;
scanstate->shared_tbmiterator = NULL;
@@ -794,20 +791,11 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
ExecInitQual(node->bitmapqualorig, (PlanState *) scanstate);
/*
- * Determine the maximum for prefetch_target. If the tablespace has a
- * specific IO concurrency set, use that to compute the corresponding
- * maximum value; otherwise, we already initialized to the value computed
- * by the GUC machinery.
+ * Maximum number of prefetches for the tablespace if configured, otherwise
+ * the current value of the effective_io_concurrency GUC.
*/
- io_concurrency =
+ scanstate->prefetch_maximum =
get_tablespace_io_concurrency(currentRelation->rd_rel->reltablespace);
- if (io_concurrency != effective_io_concurrency)
- {
- double maximum;
-
- if (ComputeIoConcurrency(io_concurrency, &maximum))
- scanstate->prefetch_maximum = rint(maximum);
- }
scanstate->ss.ss_currentRelation = currentRelation;
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 5880054245..7a7748b695 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -110,6 +110,13 @@ bool zero_damaged_pages = false;
int bgwriter_lru_maxpages = 100;
double bgwriter_lru_multiplier = 2.0;
bool track_io_timing = false;
+
+/*
+ * How many buffers PrefetchBuffer callers should try to stay ahead of their
+ * ReadBuffer calls by. Zero means "never prefetch". This value is only used
+ * for buffers not belonging to tablespaces that have their
+ * effective_io_concurrency parameter set.
+ */
int effective_io_concurrency = 0;
/*
@@ -120,15 +127,6 @@ int checkpoint_flush_after = 0;
int bgwriter_flush_after = 0;
int backend_flush_after = 0;
-/*
- * How many buffers PrefetchBuffer callers should try to stay ahead of their
- * ReadBuffer calls by. This is maintained by the assign hook for
- * effective_io_concurrency. Zero means "never prefetch". This value is
- * only used for buffers not belonging to tablespaces that have their
- * effective_io_concurrency parameter set.
- */
-int target_prefetch_pages = 0;
-
/* local state for StartBufferIO and related functions */
static BufferDesc *InProgressBuf = NULL;
static bool IsForInput;
@@ -461,64 +459,6 @@ static int ckpt_buforder_comparator(const void *pa, const void *pb);
static int ts_ckpt_progress_comparator(Datum a, Datum b, void *arg);
-/*
- * ComputeIoConcurrency -- get the number of pages to prefetch for a given
- * number of spindles.
- */
-bool
-ComputeIoConcurrency(int io_concurrency, double *target)
-{
- double new_prefetch_pages = 0.0;
- int i;
-
- /*
- * Make sure the io_concurrency value is within valid range; it may have
- * been forced with a manual pg_tablespace update.
- */
- io_concurrency = Min(Max(io_concurrency, 0), MAX_IO_CONCURRENCY);
-
- /*----------
- * The user-visible GUC parameter is the number of drives (spindles),
- * which we need to translate to a number-of-pages-to-prefetch target.
- * The target value is stashed in *extra and then assigned to the actual
- * variable by assign_effective_io_concurrency.
- *
- * The expected number of prefetch pages needed to keep N drives busy is:
- *
- * drives | I/O requests
- * -------+----------------
- * 1 | 1
- * 2 | 2/1 + 2/2 = 3
- * 3 | 3/1 + 3/2 + 3/3 = 5 1/2
- * 4 | 4/1 + 4/2 + 4/3 + 4/4 = 8 1/3
- * n | n * H(n)
- *
- * This is called the "coupon collector problem" and H(n) is called the
- * harmonic series. This could be approximated by n * ln(n), but for
- * reasonable numbers of drives we might as well just compute the series.
- *
- * Alternatively we could set the target to the number of pages necessary
- * so that the expected number of active spindles is some arbitrary
- * percentage of the total. This sounds the same but is actually slightly
- * different. The result ends up being ln(1-P)/ln((n-1)/n) where P is
- * that desired fraction.
- *
- * Experimental results show that both of these formulas aren't aggressive
- * enough, but we don't really have any better proposals.
- *
- * Note that if io_concurrency = 0 (disabled), we must set target = 0.
- *----------
- */
-
- for (i = 1; i <= io_concurrency; i++)
- new_prefetch_pages += (double) io_concurrency / (double) i;
-
- *target = new_prefetch_pages;
-
- /* This range check shouldn't fail, but let's be paranoid */
- return (new_prefetch_pages >= 0.0 && new_prefetch_pages < (double) INT_MAX);
-}
-
/*
* PrefetchBuffer -- initiate asynchronous read of a block of a relation
*
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index c1fad3b350..45dbf270bf 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -195,7 +195,6 @@ static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource so
static bool check_max_wal_senders(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);
static bool check_application_name(char **newval, void **extra, GucSource source);
static void assign_application_name(const char *newval, void *extra);
@@ -2881,7 +2880,7 @@ static struct config_int ConfigureNamesInt[] =
0,
#endif
0, MAX_IO_CONCURRENCY,
- check_effective_io_concurrency, assign_effective_io_concurrency, NULL
+ check_effective_io_concurrency, NULL, NULL
},
{
@@ -11456,36 +11455,14 @@ check_max_worker_processes(int *newval, void **extra, GucSource source)
static bool
check_effective_io_concurrency(int *newval, void **extra, GucSource source)
{
-#ifdef USE_PREFETCH
- double new_prefetch_pages;
-
- if (ComputeIoConcurrency(*newval, &new_prefetch_pages))
- {
- int *myextra = (int *) guc_malloc(ERROR, sizeof(int));
-
- *myextra = (int) rint(new_prefetch_pages);
- *extra = (void *) myextra;
-
- return true;
- }
- else
- return false;
-#else
+#ifndef USE_PREFETCH
if (*newval != 0)
{
GUC_check_errdetail("effective_io_concurrency must be set to 0 on platforms that lack posix_fadvise().");
return false;
}
- return true;
-#endif /* USE_PREFETCH */
-}
-
-static void
-assign_effective_io_concurrency(int newval, void *extra)
-{
-#ifdef USE_PREFETCH
- target_prefetch_pages = *((int *) extra);
#endif /* USE_PREFETCH */
+ return true;
}
static void
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 73c7e9ba38..0b082ea79f 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -161,7 +161,6 @@ extern PGDLLIMPORT int32 *LocalRefCount;
/*
* prototypes for functions in bufmgr.c
*/
-extern bool ComputeIoConcurrency(int io_concurrency, double *target);
extern void PrefetchBuffer(Relation reln, ForkNumber forkNum,
BlockNumber blockNum);
extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
--
2.20.1
From d7f04fbbea2d69530be9ea13b7dfb175d37c319c Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.mu...@gmail.com>
Date: Tue, 10 Mar 2020 11:49:40 +1300
Subject: [PATCH 2/2] Introduce a maintenance_io_concurrency setting.
Introduce a GUC and a tablespace option to control I/O prefetching, much
like effective_io_concurrency, but for maintenance tasks that act on
behalf of many regular user backends.
Use the new setting in heapam.c instead of the hard-coded formula
effective_io_concurrency + 10 introduced by commit 558a9165e08. Take
inspiration from that commit to choose a default value of 10 for
maintenance_io_concurrency.
Discussion: https://postgr.es/m/CA%2BhUKGJUw08dPs_3EUcdO6M90GnjofPYrWp4YSLaBkgYwS-AqA%40mail.gmail.com
---
doc/src/sgml/config.sgml | 16 +++++++++++++
doc/src/sgml/ref/alter_tablespace.sgml | 11 +++++----
doc/src/sgml/ref/create_tablespace.sgml | 11 +++++----
src/backend/access/common/reloptions.c | 16 ++++++++++++-
src/backend/access/heap/heapam.c | 16 +++----------
src/backend/storage/buffer/bufmgr.c | 6 +++++
src/backend/utils/cache/spccache.c | 14 +++++++++++
src/backend/utils/misc/guc.c | 32 +++++++++++++++++++++++++
src/bin/psql/tab-complete.c | 2 +-
src/include/commands/tablespace.h | 1 +
src/include/storage/bufmgr.h | 1 +
src/include/utils/spccache.h | 1 +
12 files changed, 104 insertions(+), 23 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index c1128f89ec..52bb3f749f 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2229,6 +2229,22 @@ include_dir 'conf.d'
</listitem>
</varlistentry>
+ <varlistentry id="guc-maintenance-io-concurrency" xreflabel="maintenance_io_concurrency">
+ <term><varname>maintenance_io_concurrency</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>maintenance_io_concurrency</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Similar to <varname>effective_io_concurrency</varname>, but used
+ for maintenance tasks such as VACUUM. The default value is higher,
+ because maintenance processes work on behalf of many concurrent
+ regular processes.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-max-worker-processes" xreflabel="max_worker_processes">
<term><varname>max_worker_processes</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/alter_tablespace.sgml b/doc/src/sgml/ref/alter_tablespace.sgml
index acec33469f..356fb9f93f 100644
--- a/doc/src/sgml/ref/alter_tablespace.sgml
+++ b/doc/src/sgml/ref/alter_tablespace.sgml
@@ -84,13 +84,16 @@ ALTER TABLESPACE <replaceable>name</replaceable> RESET ( <replaceable class="par
<para>
A tablespace parameter to be set or reset. Currently, the only
available parameters are <varname>seq_page_cost</varname>,
- <varname>random_page_cost</varname> and <varname>effective_io_concurrency</varname>.
- Setting either value for a particular tablespace will override the
+ <varname>random_page_cost</varname>, <varname>effective_io_concurrency</varname>
+ and <varname>maintenance_io_concurrency</varname>.
+ Setting these values for a particular tablespace will override the
planner's usual estimate of the cost of reading pages from tables in
- that tablespace, as established by the configuration parameters of the
+ that tablespace, and the executor's prefetching behavior, as established
+ by the configuration parameters of the
same name (see <xref linkend="guc-seq-page-cost"/>,
<xref linkend="guc-random-page-cost"/>,
- <xref linkend="guc-effective-io-concurrency"/>). This may be useful if
+ <xref linkend="guc-effective-io-concurrency"/>,
+ <xref linkend="guc-maintenance-io-concurrency"/>). This may be useful if
one tablespace is located on a disk which is faster or slower than the
remainder of the I/O subsystem.
</para>
diff --git a/doc/src/sgml/ref/create_tablespace.sgml b/doc/src/sgml/ref/create_tablespace.sgml
index c621ec2c6b..462b8831c2 100644
--- a/doc/src/sgml/ref/create_tablespace.sgml
+++ b/doc/src/sgml/ref/create_tablespace.sgml
@@ -106,13 +106,16 @@ CREATE TABLESPACE <replaceable class="parameter">tablespace_name</replaceable>
<para>
A tablespace parameter to be set or reset. Currently, the only
available parameters are <varname>seq_page_cost</varname>,
- <varname>random_page_cost</varname> and <varname>effective_io_concurrency</varname>.
- Setting either value for a particular tablespace will override the
+ <varname>random_page_cost</varname>, <varname>effective_io_concurrency</varname>
+ and <varname>maintenance_io_concurrency</varname>.
+ Setting these values for a particular tablespace will override the
planner's usual estimate of the cost of reading pages from tables in
- that tablespace, as established by the configuration parameters of the
+ that tablespace, and the executor's prefetching behavior, as established
+ by the configuration parameters of the
same name (see <xref linkend="guc-seq-page-cost"/>,
<xref linkend="guc-random-page-cost"/>,
- <xref linkend="guc-effective-io-concurrency"/>). This may be useful if
+ <xref linkend="guc-effective-io-concurrency"/>,
+ <xref linkend="guc-maintenance-io-concurrency"/>). This may be useful if
one tablespace is located on a disk which is faster or slower than the
remainder of the I/O subsystem.
</para>
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index c3d45c7a24..654ed7993a 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -349,6 +349,19 @@ static relopt_int intRelOpts[] =
-1, 0, MAX_IO_CONCURRENCY
#else
0, 0, 0
+#endif
+ },
+ {
+ {
+ "maintenance_io_concurrency",
+ "Number of simultaneous requests that can be handled efficiently by the disk subsystem for maintenance tasks.",
+ RELOPT_KIND_TABLESPACE,
+ ShareUpdateExclusiveLock
+ },
+#ifdef USE_PREFETCH
+ -1, 0, MAX_IO_CONCURRENCY
+#else
+ 0, 0, 0
#endif
},
{
@@ -1700,7 +1713,8 @@ tablespace_reloptions(Datum reloptions, bool validate)
static const relopt_parse_elt tab[] = {
{"random_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, random_page_cost)},
{"seq_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, seq_page_cost)},
- {"effective_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, effective_io_concurrency)}
+ {"effective_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, effective_io_concurrency)},
+ {"maintenance_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, maintenance_io_concurrency)}
};
return (bytea *) build_reloptions(reloptions, validate,
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 5a32e62ed0..29694b8aa4 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7003,7 +7003,6 @@ heap_compute_xid_horizon_for_tuples(Relation rel,
Page hpage;
#ifdef USE_PREFETCH
XidHorizonPrefetchState prefetch_state;
- int io_concurrency;
int prefetch_distance;
#endif
@@ -7026,24 +7025,15 @@ heap_compute_xid_horizon_for_tuples(Relation rel,
/*
* Compute the prefetch distance that we will attempt to maintain.
*
- * We don't use the regular formula to determine how much to prefetch
- * here, but instead just add a constant to effective_io_concurrency.
- * That's because it seems best to do some prefetching here even when
- * effective_io_concurrency is set to 0, but if the DBA thinks it's OK to
- * do more prefetching for other operations, then it's probably OK to do
- * more prefetching in this case, too. It may be that this formula is too
- * simplistic, but at the moment there is no evidence of that or any idea
- * about what would work better.
- *
* Since the caller holds a buffer lock somewhere in rel, we'd better make
* sure that isn't a catalog relation before we call code that does
* syscache lookups, to avoid risk of deadlock.
*/
if (IsCatalogRelation(rel))
- io_concurrency = effective_io_concurrency;
+ prefetch_distance = maintenance_io_concurrency;
else
- io_concurrency = get_tablespace_io_concurrency(rel->rd_rel->reltablespace);
- prefetch_distance = Min((io_concurrency) + 10, MAX_IO_CONCURRENCY);
+ prefetch_distance =
+ get_tablespace_maintenance_io_concurrency(rel->rd_rel->reltablespace);
/* Start prefetching. */
xid_horizon_prefetch_buffer(rel, &prefetch_state, prefetch_distance);
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 7a7748b695..7ab3577ad4 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -119,6 +119,12 @@ bool track_io_timing = false;
*/
int effective_io_concurrency = 0;
+/*
+ * Like effective_io_concurrency, but used by maintenance code paths that might
+ * benefit from a higher setting because they work on behalf of many backends.
+ */
+int maintenance_io_concurrency = 0;
+
/*
* GUC variables about triggering kernel writeback for buffers written; OS
* dependent defaults are set via the GUC mechanism.
diff --git a/src/backend/utils/cache/spccache.c b/src/backend/utils/cache/spccache.c
index c4a0f719fb..e0c3c1b1c1 100644
--- a/src/backend/utils/cache/spccache.c
+++ b/src/backend/utils/cache/spccache.c
@@ -221,3 +221,17 @@ get_tablespace_io_concurrency(Oid spcid)
else
return spc->opts->effective_io_concurrency;
}
+
+/*
+ * get_tablespace_maintenance_io_concurrency
+ */
+int
+get_tablespace_maintenance_io_concurrency(Oid spcid)
+{
+ TableSpaceCacheEntry *spc = get_tablespace(spcid);
+
+ if (!spc->opts || spc->opts->maintenance_io_concurrency < 0)
+ return maintenance_io_concurrency;
+ else
+ return spc->opts->maintenance_io_concurrency;
+}
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 45dbf270bf..668870f30f 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -195,6 +195,7 @@ static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource so
static bool check_max_wal_senders(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 bool check_maintenance_io_concurrency(int *newval, void **extra, GucSource source);
static void assign_pgstat_temp_directory(const char *newval, void *extra);
static bool check_application_name(char **newval, void **extra, GucSource source);
static void assign_application_name(const char *newval, void *extra);
@@ -2883,6 +2884,24 @@ static struct config_int ConfigureNamesInt[] =
check_effective_io_concurrency, NULL, NULL
},
+ {
+ {"maintenance_io_concurrency",
+ PGC_USERSET,
+ RESOURCES_ASYNCHRONOUS,
+ gettext_noop("Like effective_io_concurrency, but a separate setting used by maintenance tasks."),
+ NULL,
+ GUC_EXPLAIN
+ },
+ &maintenance_io_concurrency,
+#ifdef USE_PREFETCH
+ 10,
+#else
+ 0,
+#endif
+ 0, MAX_IO_CONCURRENCY,
+ check_maintenance_io_concurrency, NULL, NULL
+ },
+
{
{"backend_flush_after", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
@@ -11465,6 +11484,19 @@ check_effective_io_concurrency(int *newval, void **extra, GucSource source)
return true;
}
+static bool
+check_maintenance_io_concurrency(int *newval, void **extra, GucSource source)
+{
+#ifndef USE_PREFETCH
+ if (*newval != 0)
+ {
+ GUC_check_errdetail("maintenance_io_concurrency must be set to 0 on platforms that lack posix_fadvise().");
+ return false;
+ }
+#endif /* USE_PREFETCH */
+ return true;
+}
+
static void
assign_pgstat_temp_directory(const char *newval, void *extra)
{
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 174c3db623..ae35fa4aa9 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2140,7 +2140,7 @@ psql_completion(const char *text, int start, int end)
/* ALTER TABLESPACE <foo> SET|RESET ( */
else if (Matches("ALTER", "TABLESPACE", MatchAny, "SET|RESET", "("))
COMPLETE_WITH("seq_page_cost", "random_page_cost",
- "effective_io_concurrency");
+ "effective_io_concurrency", "maintenance_io_concurrency");
/* ALTER TEXT SEARCH */
else if (Matches("ALTER", "TEXT", "SEARCH"))
diff --git a/src/include/commands/tablespace.h b/src/include/commands/tablespace.h
index 41c457052d..fd1b28fca2 100644
--- a/src/include/commands/tablespace.h
+++ b/src/include/commands/tablespace.h
@@ -40,6 +40,7 @@ typedef struct TableSpaceOpts
float8 random_page_cost;
float8 seq_page_cost;
int effective_io_concurrency;
+ int maintenance_io_concurrency;
} TableSpaceOpts;
extern Oid CreateTableSpace(CreateTableSpaceStmt *stmt);
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 0b082ea79f..428d8005e7 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -68,6 +68,7 @@ extern PGDLLIMPORT char *BufferBlocks;
/* in guc.c */
extern int effective_io_concurrency;
+extern int maintenance_io_concurrency;
/* in localbuf.c */
extern PGDLLIMPORT int NLocBuffer;
diff --git a/src/include/utils/spccache.h b/src/include/utils/spccache.h
index 5112ba3c37..7e4ec69aa2 100644
--- a/src/include/utils/spccache.h
+++ b/src/include/utils/spccache.h
@@ -16,5 +16,6 @@
void get_tablespace_page_costs(Oid spcid, float8 *spc_random_page_cost,
float8 *spc_seq_page_cost);
int get_tablespace_io_concurrency(Oid spcid);
+int get_tablespace_maintenance_io_concurrency(Oid spcid);
#endif /* SPCCACHE_H */
--
2.20.1
