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In v11, disable JIT by default (it's still enabled by default in HEAD).

Browse Source 
Per discussion, JIT isn't quite mature enough to ship enabled-by-default.

I failed to resist the temptation to do a bunch of copy-editing on the
related documentation.  Also, clean up some inconsistencies in which
section of config.sgml the JIT GUCs are documented in vs. what guc.c
and postgresql.config.sample had.

Discussion: https://postgr.es/m/20180914222657.mw25esrzbcnu6qlu@alap3.anarazel.de
pull/34/head
Tom Lane 7 years ago
parent 1f4a920b73
commit 8f32bacc00
6 changed files with 142 additions and 145 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 87
      doc/src/sgml/config.sgml
  2. 169
      doc/src/sgml/jit.sgml
  3. 12
      doc/src/sgml/release-11.sgml
  4. 2
      src/backend/jit/jit.c
  5. 2
      src/backend/utils/misc/guc.c
  6. 15
      src/backend/utils/misc/postgresql.conf.sample

87
doc/src/sgml/config.sgml
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@ -4155,7 +4155,6 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry id="guc-jit-above-cost" xreflabel="jit_above_cost"> <varlistentry id="guc-jit-above-cost" xreflabel="jit_above_cost">
<term><varname>jit_above_cost</varname> (<type>floating point</type>) <term><varname>jit_above_cost</varname> (<type>floating point</type>)
<indexterm> <indexterm>
@ -4164,48 +4163,49 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
</term> </term>
<listitem> <listitem>
<para> <para>
Sets the planner's cutoff above which JIT compilation is used as part Sets the query cost above which JIT compilation is activated, if
of query execution (see <xref linkend="jit"/>). Performing enabled (see <xref linkend="jit"/>).
<acronym>JIT</acronym> costs time but can accelerate query execution. Performing <acronym>JIT</acronym> costs planning time but can
accelerate query execution.
Setting this to <literal>-1</literal> disables JIT compilation.
The default is <literal>100000</literal>. The default is <literal>100000</literal>.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry id="guc-jit-optimize-above-cost" xreflabel="jit_optimize_above_cost"> <varlistentry id="guc-jit-inline-above-cost" xreflabel="jit_inline_above_cost">
<term><varname>jit_optimize_above_cost</varname> (<type>floating point</type>) <term><varname>jit_inline_above_cost</varname> (<type>floating point</type>)
<indexterm> <indexterm>
<primary><varname>jit_optimize_above_cost</varname> configuration parameter</primary> <primary><varname>jit_inline_above_cost</varname> configuration parameter</primary>
</indexterm> </indexterm>
</term> </term>
<listitem> <listitem>
<para> <para>
Sets the planner's cutoff above which JIT compiled programs (see <xref Sets the query cost above which JIT compilation attempts to inline
linkend="guc-jit-above-cost"/>) are optimized. Optimization initially functions and operators. Inlining adds planning time, but can
takes time, but can improve execution speed. It is not meaningful to improve execution speed. It is not meaningful to set this to less
set this to a lower value than <xref linkend="guc-jit-above-cost"/>. than <varname>jit_above_cost</varname>.
Setting this to <literal>-1</literal> disables inlining.
The default is <literal>500000</literal>. The default is <literal>500000</literal>.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry id="guc-jit-inline-above-cost" xreflabel="jit_inline_above_cost"> <varlistentry id="guc-jit-optimize-above-cost" xreflabel="jit_optimize_above_cost">
<term><varname>jit_inline_above_cost</varname> (<type>floating point</type>) <term><varname>jit_optimize_above_cost</varname> (<type>floating point</type>)
<indexterm> <indexterm>
<primary><varname>jit_inline_above_cost</varname> configuration parameter</primary> <primary><varname>jit_optimize_above_cost</varname> configuration parameter</primary>
</indexterm> </indexterm>
</term> </term>
<listitem> <listitem>
<para> <para>
Sets the planner's cutoff above which JIT compiled programs (see <xref Sets the query cost above which JIT compilation applies expensive
linkend="guc-jit-above-cost"/>) attempt to inline functions and optimizations. Such optimization adds planning time, but can improve
operators. Inlining initially takes time, but can improve execution execution speed. It is not meaningful to set this to less
speed. It is unlikely to be beneficial to set than <varname>jit_above_cost</varname>, and it is unlikely to be
<varname>jit_inline_above_cost</varname> below beneficial to set it to more
<varname>jit_optimize_above_cost</varname>. than <varname>jit_inline_above_cost</varname>.
Setting this to <literal>-1</literal> disables expensive optimizations.
The default is <literal>500000</literal>. The default is <literal>500000</literal>.
</para> </para>
</listitem> </listitem>
@ -4500,10 +4500,9 @@ SELECT * FROM parent WHERE key = 2400;
</term> </term>
<listitem> <listitem>
<para> <para>
Determines whether <acronym>JIT</acronym> may be used by Determines whether <acronym>JIT</acronym> compilation may be used by
<productname>PostgreSQL</productname>, if available (see <xref <productname>PostgreSQL</productname>, if available (see <xref
linkend="jit"/>). linkend="jit"/>).
The default is <literal>on</literal>. The default is <literal>on</literal>.
</para> </para>
</listitem> </listitem>
@ -7582,16 +7581,17 @@ SET XML OPTION { DOCUMENT | CONTENT };
</term> </term>
<listitem> <listitem>
<para> <para>
Determines which JIT provider (see <xref linkend="jit-extensibility"/>) is This variable is the name of the JIT provider library to be used
used. The built-in default is <literal>llvmjit</literal>. (see <xref linkend="jit-pluggable"/>).
The default is <literal>llvmjit</literal>.
This parameter can only be set at server start.
</para> </para>
<para> <para>
If set to a non-existent library <acronym>JIT</acronym> will not be If set to a non-existent library, <acronym>JIT</acronym> will not be
available, but no error will be raised. This allows JIT support to be available, but no error will be raised. This allows JIT support to be
installed separately from the main installed separately from the main
<productname>PostgreSQL</productname> package. <productname>PostgreSQL</productname> package.
This parameter can only be set at server start.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -8886,9 +8886,8 @@ LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
<para> <para>
If LLVM has the required functionality, register generated functions If LLVM has the required functionality, register generated functions
with <productname>GDB</productname>. This makes debugging easier. with <productname>GDB</productname>. This makes debugging easier.
The default setting is <literal>off</literal>.
The default setting is <literal>off</literal>, and can only be set at This parameter can only be set at server start.
server start.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -8904,9 +8903,8 @@ LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
Writes the generated <productname>LLVM</productname> IR out to the Writes the generated <productname>LLVM</productname> IR out to the
file system, inside <xref linkend="guc-data-directory"/>. This is only file system, inside <xref linkend="guc-data-directory"/>. This is only
useful for working on the internals of the JIT implementation. useful for working on the internals of the JIT implementation.
The default setting is <literal>off</literal>.
The default setting is <literal>off</literal>, and it can only be This parameter can only be changed by a superuser.
changed by a superuser.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -8919,8 +8917,8 @@ LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
</term> </term>
<listitem> <listitem>
<para> <para>
Determines whether expressions are JIT compiled, subject to costing Determines whether expressions are JIT compiled, when JIT compilation
decisions (see <xref linkend="jit-decision"/>). The default is is activated (see <xref linkend="jit-decision"/>). The default is
<literal>on</literal>. <literal>on</literal>.
</para> </para>
</listitem> </listitem>
@ -8934,13 +8932,12 @@ LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
</term> </term>
<listitem> <listitem>
<para> <para>
If LLVM has the required functionality, emit required data to allow If LLVM has the required functionality, emit the data needed to allow
<productname>perf</productname> to profile functions generated by JIT. <productname>perf</productname> to profile functions generated by JIT.
This writes out files to <filename>$HOME/.debug/jit/</filename>; the This writes out files to <filename>$HOME/.debug/jit/</filename>; the
user is responsible for performing cleanup when desired. user is responsible for performing cleanup when desired.
The default setting is <literal>off</literal>.
The default setting is <literal>off</literal>, and can only be set at This parameter can only be set at server start.
server start.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -8953,9 +8950,9 @@ LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
</term> </term>
<listitem> <listitem>
<para> <para>
Determines whether tuple deforming is JIT compiled, subject to costing Determines whether tuple deforming is JIT compiled, when JIT
decisions (see <xref linkend="jit-decision"/>). The default is compilation is activated (see <xref linkend="jit-decision"/>).
<literal>on</literal>. The default is <literal>on</literal>.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>

169
doc/src/sgml/jit.sgml
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@ -21,22 +21,22 @@
<title>What is <acronym>JIT</acronym> compilation?</title> <title>What is <acronym>JIT</acronym> compilation?</title>
<para> <para>
Just-in-time compilation (<acronym>JIT</acronym>) is the process of turning Just-in-Time (<acronym>JIT</acronym>) compilation is the process of turning
some form of interpreted program evaluation into a native program, and some form of interpreted program evaluation into a native program, and
doing so at run time. doing so at run time.
For example, instead of using general-purpose code that can evaluate
For example, instead of using a facility that can evaluate arbitrary SQL arbitrary SQL expressions to evaluate a particular SQL predicate
expressions to evaluate an SQL predicate like <literal>WHERE a.col = like <literal>WHERE a.col = 3</literal>, it is possible to generate a
3</literal>, it is possible to generate a function than can be natively function that is specific to that expression and can be natively executed
executed by the CPU that just handles that expression, yielding a speedup. by the CPU, yielding a speedup.
</para> </para>
<para> <para>
<productname>PostgreSQL</productname> has builtin support to perform <productname>PostgreSQL</productname> has builtin support to perform
<acronym>JIT</acronym> compilation using <ulink <acronym>JIT</acronym> compilation using <ulink
url="https://llvm.org/"><productname>LLVM</productname></ulink> when url="https://llvm.org/"><productname>LLVM</productname></ulink> when
<productname>PostgreSQL</productname> was built with <productname>PostgreSQL</productname> is built with
<literal>--with-llvm</literal> (see <xref linkend="configure-with-llvm"/>). <link linkend="configure-with-llvm"><literal>--with-llvm</literal></link>.
</para> </para>
<para> <para>
@ -64,33 +64,32 @@
</para> </para>
</sect2> </sect2>
<sect2 id="jit-optimization">
<title>Optimization</title>
<para>
<productname>LLVM</productname> has support for optimizing generated
code. Some of the optimizations are cheap enough to be performed whenever
<acronym>JIT</acronym> is used, while others are only beneficial for
longer running queries.
See <ulink url="https://llvm.org/docs/Passes.html#transform-passes"/> for
more details about optimizations.
</para>
</sect2>
<sect2 id="jit-inlining"> <sect2 id="jit-inlining">
<title>Inlining</title> <title>Inlining</title>
<para> <para>
<productname>PostgreSQL</productname> is very extensible and allows new <productname>PostgreSQL</productname> is very extensible and allows new
data types, functions, operators and other database objects to be defined; data types, functions, operators and other database objects to be defined;
see <xref linkend="extend"/>. In fact the built-in ones are implemented see <xref linkend="extend"/>. In fact the built-in objects are implemented
using nearly the same mechanisms. This extensibility implies some using nearly the same mechanisms. This extensibility implies some
overhead, for example due to function calls (see <xref linkend="xfunc"/>). overhead, for example due to function calls (see <xref linkend="xfunc"/>).
To reduce that overhead <acronym>JIT</acronym> compilation can inline the To reduce that overhead, <acronym>JIT</acronym> compilation can inline the
body for small functions into the expression using them. That allows a bodies of small functions into the expressions using them. That allows a
significant percentage of the overhead to be optimized away. significant percentage of the overhead to be optimized away.
</para> </para>
</sect2> </sect2>
<sect2 id="jit-optimization">
<title>Optimization</title>
<para>
<productname>LLVM</productname> has support for optimizing generated
code. Some of the optimizations are cheap enough to be performed whenever
<acronym>JIT</acronym> is used, while others are only beneficial for
longer-running queries.
See <ulink url="https://llvm.org/docs/Passes.html#transform-passes"/> for
more details about optimizations.
</para>
</sect2>
</sect1> </sect1>
<sect1 id="jit-decision"> <sect1 id="jit-decision">
@ -98,50 +97,46 @@
<para> <para>
<acronym>JIT</acronym> compilation is beneficial primarily for long-running <acronym>JIT</acronym> compilation is beneficial primarily for long-running
CPU bound queries. Frequently these will be analytical queries. For short CPU-bound queries. Frequently these will be analytical queries. For short
queries the added overhead of performing <acronym>JIT</acronym> compilation queries the added overhead of performing <acronym>JIT</acronym> compilation
will often be higher than the time it can save. will often be higher than the time it can save.
</para> </para>
<para> <para>
To determine whether <acronym>JIT</acronym> compilation is used, the total To determine whether <acronym>JIT</acronym> compilation should be used,
cost of a query (see <xref linkend="planner-stats-details"/> and <xref the total estimated cost of a query (see
linkend="runtime-config-query-constants"/>) is used. <xref linkend="planner-stats-details"/> and
</para> <xref linkend="runtime-config-query-constants"/>) is used.
The estimated cost of the query will be compared with the setting of <xref
<para>
The cost of the query will be compared with the setting of <xref
linkend="guc-jit-above-cost"/>. If the cost is higher, linkend="guc-jit-above-cost"/>. If the cost is higher,
<acronym>JIT</acronym> compilation will be performed. <acronym>JIT</acronym> compilation will be performed.
</para> Two further decisions are then needed.
Firstly, if the estimated cost is more
<para> than the setting of <xref linkend="guc-jit-inline-above-cost"/>, short
If the planner, based on the above criterion, decided that functions and operators used in the query will be inlined.
<acronym>JIT</acronym> compilation is beneficial, two further decisions are Secondly, if the estimated cost is more than the setting of <xref
made. Firstly, if the query is more costly than the setting of <xref
linkend="guc-jit-optimize-above-cost"/>, expensive optimizations are linkend="guc-jit-optimize-above-cost"/>, expensive optimizations are
used to improve the generated code. Secondly, if the query is more costly applied to improve the generated code.
than the setting of <xref linkend="guc-jit-inline-above-cost"/>, short functions Each of these options increases the <acronym>JIT</acronym> compilation
and operators used in the query will be inlined. Both of these operations overhead, but can reduce query execution time considerably.
increase the <acronym>JIT</acronym> overhead, but can reduce query
execution time considerably.
</para> </para>
<para> <para>
This cost based decision will be made at plan time, not execution These cost-based decisions will be made at plan time, not execution
time. This means that when prepared statements are in use, and the generic time. This means that when prepared statements are in use, and a generic
plan is used (see <xref linkend="sql-prepare-notes"/>), the values of the plan is used (see <xref linkend="sql-prepare"/>), the values of the
configuration parameters set at prepare time take effect, not the settings at execution time. configuration parameters in effect at prepare time control the decisions,
not the settings at execution time.
</para> </para>
<note> <note>
<para> <para>
If <xref linkend="guc-jit"/> is set to <literal>off</literal>, or no If <xref linkend="guc-jit"/> is set to <literal>off</literal>, or if no
<acronym>JIT</acronym> implementation is available (for example because <acronym>JIT</acronym> implementation is available (for example because
the server was compiled without <literal>--with-llvm</literal>), the server was compiled without <literal>--with-llvm</literal>),
<acronym>JIT</acronym> will not be performed, even if considered to be <acronym>JIT</acronym> will not be performed, even if it would be
beneficial based on the above criteria. Setting <xref linkend="guc-jit"/> beneficial based on the above criteria. Setting <xref linkend="guc-jit"/>
to <literal>off</literal> takes effect both at plan and at execution time. to <literal>off</literal> has effects at both plan and execution time.
</para> </para>
</note> </note>
@ -160,9 +155,9 @@
(4 rows) (4 rows)
</screen> </screen>
Given the cost of the plan, it is entirely reasonable that no Given the cost of the plan, it is entirely reasonable that no
<acronym>JIT</acronym> was used, the cost of <acronym>JIT</acronym> would <acronym>JIT</acronym> was used; the cost of <acronym>JIT</acronym> would
have been bigger than the savings. Adjusting the cost limits will lead to have been bigger than the potential savings. Adjusting the cost limits
<acronym>JIT</acronym> use: will lead to <acronym>JIT</acronym> use:
<screen> <screen>
=# SET jit_above_cost = 10; =# SET jit_above_cost = 10;
SET SET
@ -184,9 +179,9 @@ SET
</screen> </screen>
As visible here, <acronym>JIT</acronym> was used, but inlining and As visible here, <acronym>JIT</acronym> was used, but inlining and
expensive optimization were not. If <xref expensive optimization were not. If <xref
linkend="guc-jit-optimize-above-cost"/>, <xref linkend="guc-jit-inline-above-cost"/> or <xref
linkend="guc-jit-inline-above-cost"/> were lowered, just like <xref linkend="guc-jit-optimize-above-cost"/> were also lowered,
linkend="guc-jit-above-cost"/>, that would change. that would change.
</para> </para>
</sect1> </sect1>
@ -194,58 +189,53 @@ SET
<title>Configuration</title> <title>Configuration</title>
<para> <para>
The configuration variable
<xref linkend="guc-jit"/> determines whether <acronym>JIT</acronym> <xref linkend="guc-jit"/> determines whether <acronym>JIT</acronym>
compilation is enabled or disabled. compilation is enabled or disabled.
</para> If it is enabled, the configuration variables
<para>
As explained in <xref linkend="jit-decision"/> the configuration variables
<xref linkend="guc-jit-above-cost"/>, <xref <xref linkend="guc-jit-above-cost"/>, <xref
linkend="guc-jit-optimize-above-cost"/>, <xref linkend="guc-jit-inline-above-cost"/>, and <xref
linkend="guc-jit-inline-above-cost"/> decide whether <acronym>JIT</acronym> linkend="guc-jit-optimize-above-cost"/> determine
compilation is performed for a query, and how much effort is spent doing whether <acronym>JIT</acronym> compilation is performed for a query,
so. and how much effort is spent doing so.
</para> </para>
<para> <para>
For development and debugging purposes a few additional configuration parameters exist. <xref <xref linkend="guc-jit-provider"/> determines which <acronym>JIT</acronym>
linkend="guc-jit-dump-bitcode"/> allows the generated bitcode to be implementation is used. It is rarely required to be changed. See <xref
inspected. <xref linkend="guc-jit-debugging-support"/> allows GDB to see linkend="jit-pluggable"/>.
generated functions. <xref linkend="guc-jit-profiling-support"/> emits
information so the <productname>perf</productname> profiler can interpret
<acronym>JIT</acronym> generated functions sensibly.
</para> </para>
<para> <para>
<xref linkend="guc-jit-provider"/> determines which <acronym>JIT</acronym> For development and debugging purposes a few additional configuration
implementation is used. It rarely is required to be changed. See <xref parameters exist, as described in
linkend="jit-pluggable"/>. <xref linkend="runtime-config-developer"/>.
</para> </para>
</sect1> </sect1>
<sect1 id="jit-extensibility" xreflabel="JIT Extensibility"> <sect1 id="jit-extensibility">
<title>Extensibility</title> <title>Extensibility</title>
<sect2 id="jit-extensibility-bitcode"> <sect2 id="jit-extensibility-bitcode">
<title>Inlining Support for Extensions</title> <title>Inlining Support for Extensions</title>
<para> <para>
<productname>PostgreSQL</productname>'s <acronym>JIT</acronym> <productname>PostgreSQL</productname>'s <acronym>JIT</acronym>
implementation can inline the implementation of operators and functions implementation can inline the bodies of functions
(of type <literal>C</literal> and <literal>internal</literal>). See <xref of types <literal>C</literal> and <literal>internal</literal>, as well as
linkend="jit-inlining"/>. To do so for functions in extensions, the operators based on such functions. To do so for functions in extensions,
definition of these functions needs to be made available. When using <link the definitions of those functions need to be made available.
linkend="extend-pgxs">PGXS</link> to build an extension against a server When using <link linkend="extend-pgxs">PGXS</link> to build an extension
that has been compiled with LLVM support, the relevant files will be against a server that has been compiled with LLVM JIT support, the
installed automatically. relevant files will be built and installed automatically.
</para> </para>
<para> <para>
The relevant files have to be installed into The relevant files have to be installed into
<filename>$pkglibdir/bitcode/$extension/</filename> and a summary of them <filename>$pkglibdir/bitcode/$extension/</filename> and a summary of them
to <filename>$pkglibdir/bitcode/$extension.index.bc</filename>, where into <filename>$pkglibdir/bitcode/$extension.index.bc</filename>, where
<literal>$pkglibdir</literal> is the directory returned by <literal>$pkglibdir</literal> is the directory returned by
<literal>pg_config --pkglibdir</literal> and <literal>$extension</literal> <literal>pg_config --pkglibdir</literal> and <literal>$extension</literal>
the base name of the extension's shared library. is the base name of the extension's shared library.
<note> <note>
<para> <para>
@ -258,14 +248,16 @@ SET
</sect2> </sect2>
<sect2 id="jit-pluggable"> <sect2 id="jit-pluggable">
<title>Pluggable <acronym>JIT</acronym> Provider</title> <title>Pluggable <acronym>JIT</acronym> Providers</title>
<para> <para>
<productname>PostgreSQL</productname> provides a <acronym>JIT</acronym> <productname>PostgreSQL</productname> provides a <acronym>JIT</acronym>
implementation based on <productname>LLVM</productname>. The interface to implementation based on <productname>LLVM</productname>. The interface to
the <acronym>JIT</acronym> provider is pluggable and the provider can be the <acronym>JIT</acronym> provider is pluggable and the provider can be
changed without recompiling. The provider is chosen via the setting <xref changed without recompiling (although currently, the build process only
linkend="guc-jit-provider"/>. provides inlining support data for <productname>LLVM</productname>).
The active provider is chosen via the setting
<xref linkend="guc-jit-provider"/>.
</para> </para>
<sect3> <sect3>
@ -275,10 +267,10 @@ SET
named shared library. The normal library search path is used to locate named shared library. The normal library search path is used to locate
the library. To provide the required <acronym>JIT</acronym> provider the library. To provide the required <acronym>JIT</acronym> provider
callbacks and to indicate that the library is actually a callbacks and to indicate that the library is actually a
<acronym>JIT</acronym> provider it needs to provide a function named <acronym>JIT</acronym> provider, it needs to provide a C function named
<function>_PG_jit_provider_init</function>. This function is passed a <function>_PG_jit_provider_init</function>. This function is passed a
struct that needs to be filled with the callback function pointers for struct that needs to be filled with the callback function pointers for
individual actions. individual actions:
<programlisting> <programlisting>
struct JitProviderCallbacks struct JitProviderCallbacks
{ {
@ -286,6 +278,7 @@ struct JitProviderCallbacks
JitProviderReleaseContextCB release_context; JitProviderReleaseContextCB release_context;
JitProviderCompileExprCB compile_expr; JitProviderCompileExprCB compile_expr;
}; };
extern void _PG_jit_provider_init(JitProviderCallbacks *cb); extern void _PG_jit_provider_init(JitProviderCallbacks *cb);
</programlisting> </programlisting>
</para> </para>

12
doc/src/sgml/release-11.sgml
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@ -85,8 +85,8 @@
<listitem> <listitem>
<para> <para>
JIT compilation of some SQL code, including support for fast evaluation Optional Just-in-Time (JIT) compilation of some SQL code, including
of expressions support for fast evaluation of expressions
</para> </para>
</listitem> </listitem>
@ -1076,10 +1076,16 @@ same commits as above
--> -->
<para> <para>
Add <link linkend="jit">Just-In-Time</link> Add <link linkend="jit">Just-in-Time</link>
(<acronym>JIT</acronym>) compilation of some parts of query plans (<acronym>JIT</acronym>) compilation of some parts of query plans
to improve execution speed (Andres Freund) to improve execution speed (Andres Freund)
</para> </para>
<para>
This feature requires <application>LLVM</application> to be
available, and it is not currently enabled by default, even in
builds that support it.
</para>
</listitem> </listitem>
<listitem> <listitem>

2
src/backend/jit/jit.c
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@ -33,7 +33,7 @@
/* GUCs */ /* GUCs */
bool jit_enabled = true; bool jit_enabled = true;
char *jit_provider = "llvmjit"; char *jit_provider = NULL;
bool jit_debugging_support = false; bool jit_debugging_support = false;
bool jit_dump_bitcode = false; bool jit_dump_bitcode = false;
bool jit_expressions = true; bool jit_expressions = true;

2
src/backend/utils/misc/guc.c
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@ -3895,7 +3895,7 @@ static struct config_string ConfigureNamesString[] =
}, },
{ {
{"jit_provider", PGC_POSTMASTER, FILE_LOCATIONS, {"jit_provider", PGC_POSTMASTER, CLIENT_CONN_PRELOAD,
gettext_noop("JIT provider to use."), gettext_noop("JIT provider to use."),
NULL, NULL,
GUC_SUPERUSER_ONLY GUC_SUPERUSER_ONLY

15
src/backend/utils/misc/postgresql.conf.sample
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@ -320,11 +320,12 @@
#parallel_setup_cost = 1000.0 # same scale as above #parallel_setup_cost = 1000.0 # same scale as above
#jit_above_cost = 100000 # perform JIT compilation if available #jit_above_cost = 100000 # perform JIT compilation if available
# and query more expensive, -1 disables # and query more expensive than this;
#jit_optimize_above_cost = 500000 # optimize JITed functions if query is # -1 disables
# more expensive, -1 disables #jit_inline_above_cost = 500000 # inline small functions if query is
#jit_inline_above_cost = 500000 # attempt to inline operators and # more expensive than this; -1 disables
# functions if query is more expensive, #jit_optimize_above_cost = 500000 # use expensive JIT optimizations if
# query is more expensive than this;
# -1 disables # -1 disables
#min_parallel_table_scan_size = 8MB #min_parallel_table_scan_size = 8MB
@ -350,6 +351,7 @@
#join_collapse_limit = 8 # 1 disables collapsing of explicit #join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses # JOIN clauses
#force_parallel_mode = off #force_parallel_mode = off
#jit = on # allow JIT compilation
#plan_cache_mode = auto # auto, force_generic_plan or #plan_cache_mode = auto # auto, force_generic_plan or
# force_custom_plan # force_custom_plan
@ -616,13 +618,12 @@
#shared_preload_libraries = '' # (change requires restart) #shared_preload_libraries = '' # (change requires restart)
#local_preload_libraries = '' #local_preload_libraries = ''
#session_preload_libraries = '' #session_preload_libraries = ''
#jit_provider = 'llvmjit' # JIT library to use
# - Other Defaults - # - Other Defaults -
#dynamic_library_path = '$libdir' #dynamic_library_path = '$libdir'
#jit = on # allow JIT compilation
#jit_provider = 'llvmjit' # JIT implementation to use
#------------------------------------------------------------------------------ #------------------------------------------------------------------------------
# LOCK MANAGEMENT # LOCK MANAGEMENT

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