Revert "Auto-tune effective_cache size to be 4x shared buffers"

This reverts commit ee1e5662d8d8330726eaef7d3110cb7add24d058, as well as
a remarkably large number of followup commits, which were mostly concerned
with the fact that the implementation didn't work terribly well.  It still
doesn't: we probably need some rather basic work in the GUC infrastructure
if we want to fully support GUCs whose default varies depending on the
value of another GUC.  Meanwhile, it also emerged that there wasn't really
consensus in favor of the definition the patch tried to implement (ie,
effective_cache_size should default to 4 times shared_buffers).  So whack
it all back to where it was.  In a followup commit, I'll do what was
recently agreed to, which is to simply change the default to a higher
value.

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 9ff230aa6d9bb725d16bfa319c19dc4217f21d00..bc5a8870444497e45609d9ff155a2f32177f49ef 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3194,16 +3194,8 @@ include 'filename'
         memory allocated by <productname>PostgreSQL</productname>, nor
         does it reserve kernel disk cache; it is used only for estimation
         purposes.  The system also does not assume data remains in
-        the disk cache between queries.
-       </para>
-
-       <para>
-        If <varname>effective_cache_size</> is set to -1, which is the
-        default, the value is replaced by an automatically selected value,
-        currently four times the size of <xref linkend="guc-shared-buffers">.
-        For recommended settings of <varname>shared_buffers</>, this should
-        give reasonable results if this database cluster can use most of the
-        memory on the server.
+        the disk cache between queries.  The default is 128 megabytes
+        (<literal>128MB</>).
        </para>
       </listitem>
      </varlistentry>

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 848065ee7b2d109d54fccc4e8b1366efb5f1edb2..0cdb7905a2fb38dee3977e09b101fd244bdbc471 100644 (file)
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -71,7 +71,6 @@
 #ifdef _MSC_VER
 #include <float.h>             /* for _isnan */
 #endif
-#include <limits.h>
 #include <math.h>
 
 #include "access/htup_details.h"
@@ -88,7 +87,6 @@
 #include "optimizer/planmain.h"
 #include "optimizer/restrictinfo.h"
 #include "parser/parsetree.h"
-#include "utils/guc.h"
 #include "utils/lsyscache.h"
 #include "utils/selfuncs.h"
 #include "utils/spccache.h"
@@ -104,7 +102,7 @@ double      cpu_tuple_cost = DEFAULT_CPU_TUPLE_COST;
 double     cpu_index_tuple_cost = DEFAULT_CPU_INDEX_TUPLE_COST;
 double     cpu_operator_cost = DEFAULT_CPU_OPERATOR_COST;
 
-int            effective_cache_size = -1;  /* will get replaced */
+int            effective_cache_size = DEFAULT_EFFECTIVE_CACHE_SIZE;
 
 Cost       disable_cost = 1.0e10;
 
@@ -4093,50 +4091,3 @@ page_size(double tuples, int width)
 {
    return ceil(relation_byte_size(tuples, width) / BLCKSZ);
 }
-
-/*
- * GUC check_hook for effective_cache_size
- */
-bool
-check_effective_cache_size(int *newval, void **extra, GucSource source)
-{
-   /*
-    * -1 is the documented way of requesting auto-tune, but we also treat
-    * zero as meaning that, since we don't consider zero a valid setting.
-    */
-   if (*newval <= 0)
-   {
-       /*
-        * Substitute the auto-tune value, being wary of overflow.
-        */
-       if (NBuffers < INT_MAX / 4)
-           *newval = NBuffers * 4;
-       else
-           *newval = INT_MAX;
-   }
-
-   Assert(*newval > 0);
-
-   return true;
-}
-
-/*
- * Initialize effective_cache_size at the end of GUC startup, or when
- * a setting in postgresql.conf is removed.
- *
- * Note: check_effective_cache_size() will have been called when the boot_val
- * was installed, but we will not have known the final value of NBuffers at
- * that time, which is why this has to be called at the end of GUC startup.
- */
-void
-set_default_effective_cache_size(void)
-{
-   /*
-    * We let check_effective_cache_size() compute the actual setting.  Note
-    * that this call is a no-op if the user has supplied a setting (since
-    * that will have a higher priority than PGC_S_DYNAMIC_DEFAULT).
-    */
-   SetConfigOption("effective_cache_size", "-1",
-                   PGC_POSTMASTER, PGC_S_DYNAMIC_DEFAULT);
-   Assert(effective_cache_size > 0);
-}

diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index ee3804052153654a01421a138b91040bf9d0f197..5d830c79d0155effd8979af2e8ec2059b5be11f5 100644 (file)
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -298,7 +298,6 @@ ProcessConfigFile(GucContext context)
    {
        InitializeGUCOptionsFromEnvironment();
        pg_timezone_abbrev_initialize();
-       set_default_effective_cache_size();
        /* this selects SQL_ASCII in processes not connected to a database */
        SetConfigOption("client_encoding", GetDatabaseEncodingName(),
                        PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 0401cd4d2a68256530b4e9d8a2872e3c91c045d1..ddd333fea40e6bc7cd41e6f745eab2f6200318af 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2512,8 +2512,8 @@ static struct config_int ConfigureNamesInt[] =
            GUC_UNIT_BLOCKS,
        },
        &effective_cache_size,
-       -1, -1, INT_MAX,
-       check_effective_cache_size, NULL, NULL
+       DEFAULT_EFFECTIVE_CACHE_SIZE, 1, INT_MAX,
+       NULL, NULL, NULL
    },
 
    {
@@ -4372,9 +4372,6 @@ SelectConfigFiles(const char *userDoption, const char *progname)
     */
    pg_timezone_abbrev_initialize();
 
-   /* Also install the correct value for effective_cache_size */
-   set_default_effective_cache_size();
-
    /*
     * Figure out where pg_hba.conf is, and make sure the path is absolute.
     */

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 70e5a5111ec08b23c00955f1408337660a7ba63f..61685f7c13f019ecd7791cf09a72df04be8814a6 100644 (file)
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -283,7 +283,7 @@
 #cpu_tuple_cost = 0.01         # same scale as above
 #cpu_index_tuple_cost = 0.005      # same scale as above
 #cpu_operator_cost = 0.0025        # same scale as above
-#effective_cache_size = -1     # -1 selects auto-tuned default
+#effective_cache_size = 128MB
 
 # - Genetic Query Optimizer -
 

diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index ec1605d1c9d73156034c3a8b1730dd8a4c0d738a..3c3c63ae100424d68402591aa951c2ff31481c59 100644 (file)
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -27,6 +27,8 @@
 #define DEFAULT_CPU_INDEX_TUPLE_COST 0.005
 #define DEFAULT_CPU_OPERATOR_COST  0.0025
 
+#define DEFAULT_EFFECTIVE_CACHE_SIZE  16384        /* measured in pages */
+
 typedef enum
 {
    CONSTRAINT_EXCLUSION_OFF,   /* do not use c_e */

diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 686a6a1d443a3a6ff0a5557e7824cb4912074ea6..c15a5bbb7b3493059524deb8db1dd6c8fd41244d 100644 (file)
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -389,8 +389,4 @@ extern void assign_search_path(const char *newval, void *extra);
 extern bool check_wal_buffers(int *newval, void **extra, GucSource source);
 extern void assign_xlog_sync_method(int new_sync_method, void *extra);
 
-/* in optimizer/path/costsize.c */
-extern bool check_effective_cache_size(int *newval, void **extra, GucSource source);
-extern void set_default_effective_cache_size(void);
-
 #endif   /* GUC_H */

diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index ec64bbe7b997c80c9d323920a51dd41c083f1e87..934488a6b59e75eafeb6e656802f696ac9c76dcf 100644 (file)
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -2759,7 +2759,6 @@ select * from tenk1 a join tenk1 b on
 --
 -- test placement of movable quals in a parameterized join tree
 --
-set effective_cache_size = '128MB';
 explain (costs off)
 select * from tenk1 t1 left join
   (tenk1 t2 join tenk1 t3 on t2.thousand = t3.unique2)

diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index f45aa145aded6994cb6cde036b8c47189c7d0ad6..275cb11fdfce5438ad7af9f7b914beea7917922e 100644 (file)
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -721,8 +721,6 @@ select * from tenk1 a join tenk1 b on
 -- test placement of movable quals in a parameterized join tree
 --
 
-set effective_cache_size = '128MB';
-
 explain (costs off)
 select * from tenk1 t1 left join
   (tenk1 t2 join tenk1 t3 on t2.thousand = t3.unique2)