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Merge pull request #221851 from Ma27/postgresql-jit-support

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postgresql: implement opt-in JIT support
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Sandro 2023-03-29 13:29:30 +02:00 • committed by GitHub
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11 changed files with 293 additions and 76 deletions
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37
nixos/modules/services/databases/postgresql.md
View file

@ -171,3 +171,40 @@ self: super: {
};
}
```
## JIT (Just-In-Time compilation) {#module-services-postgres-jit}
[JIT](https://www.postgresql.org/docs/current/jit-reason.html)-support in the PostgreSQL package
is disabled by default because of the ~300MiB closure-size increase from the LLVM dependency. It
can be optionally enabled in PostgreSQL with the following config option:
```nix
{
services.postgresql.enableJIT = true;
}
```
This makes sure that the [`jit`](https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-JIT)-setting
is set to `on` and a PostgreSQL package with JIT enabled is used. Further tweaking of the JIT compiler, e.g. setting a different
query cost threshold via [`jit_above_cost`](https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-JIT-ABOVE-COST)
can be done manually via [`services.postgresql.settings`](#opt-services.postgresql.settings).
The attribute-names of JIT-enabled PostgreSQL packages are suffixed with `_jit`, i.e. for each `pkgs.postgresql`
(and `pkgs.postgresql_<major>`) in `nixpkgs` there's also a `pkgs.postgresql_jit` (and `pkgs.postgresql_<major>_jit`).
Alternatively, a JIT-enabled variant can be derived from a given `postgresql` package via `postgresql.withJIT`.
This is also useful if it's not clear which attribute from `nixpkgs` was originally used (e.g. when working with
[`config.services.postgresql.package`](#opt-services.postgresql.package) or if the package was modified via an
overlay) since all modifications are propagated to `withJIT`. I.e.
```nix
with import <nixpkgs> {
overlays = [
(self: super: {
postgresql = super.postgresql.overrideAttrs (_: { pname = "foobar"; });
})
];
};
postgresql.withJIT.pname
```
evaluates to `"foobar"`.

27
nixos/modules/services/databases/postgresql.nix
View file

@ -7,9 +7,18 @@ let
cfg = config.services.postgresql;
postgresql =
let
# ensure that
# services.postgresql = {
# enableJIT = true;
# package = pkgs.postgresql_<major>;
# };
# works.
base = if cfg.enableJIT && !cfg.package.jitSupport then cfg.package.withJIT else cfg.package;
in
if cfg.extraPlugins == []
then cfg.package
else cfg.package.withPackages (_: cfg.extraPlugins);
then base
else base.withPackages (_: cfg.extraPlugins);
toStr = value:
if true == value then "yes"
@ -42,6 +51,8 @@ in
enable = mkEnableOption (lib.mdDoc "PostgreSQL Server");
enableJIT = mkEnableOption (lib.mdDoc "JIT support");
package = mkOption {
type = types.package;
example = literalExpression "pkgs.postgresql_11";
@ -435,19 +446,21 @@ in
log_line_prefix = cfg.logLinePrefix;
listen_addresses = if cfg.enableTCPIP then "*" else "localhost";
port = cfg.port;
jit = mkDefault (if cfg.enableJIT then "on" else "off");
};
services.postgresql.package = let
mkThrow = ver: throw "postgresql_${ver} was removed, please upgrade your postgresql version.";
base = if versionAtLeast config.system.stateVersion "22.05" then pkgs.postgresql_14
else if versionAtLeast config.system.stateVersion "21.11" then pkgs.postgresql_13
else if versionAtLeast config.system.stateVersion "20.03" then pkgs.postgresql_11
else if versionAtLeast config.system.stateVersion "17.09" then mkThrow "9_6"
else mkThrow "9_5";
in
# Note: when changing the default, make it conditional on
# ‘system.stateVersion’ to maintain compatibility with existing
# systems!
mkDefault (if versionAtLeast config.system.stateVersion "22.05" then pkgs.postgresql_14
else if versionAtLeast config.system.stateVersion "21.11" then pkgs.postgresql_13
else if versionAtLeast config.system.stateVersion "20.03" then pkgs.postgresql_11
else if versionAtLeast config.system.stateVersion "17.09" then mkThrow "9_6"
else mkThrow "9_5");
mkDefault (if cfg.enableJIT then base.withJIT else base);
services.postgresql.dataDir = mkDefault "/var/lib/postgresql/${cfg.package.psqlSchema}";