fix(db): remove temp_store = MEMORY pragmas (#10343)

This reduces database migration memory usage in my test scenario from
3.8 GB to 440 MB. In principle I don't think we're causing many temp
tables to be generated anyway in normal usage, but if we do and someone
can benchmark a performance difference, we can add a tunable. I ran the
database benchmark before and after and didn't see a difference above
the noise level.

Signed-off-by: Jakob Borg <jakob@kastelo.net>

CONTRIBUTING.md

@@ -34,19 +34,163 @@ Note that the previously used service at
 retired and we kindly ask you to sign up on Weblate for continued
 involvement.
 
-## Contributing Code
-
-Every contribution is welcome. If you want to contribute but are unsure
-where to start, any open issues are fair game! See the [Contribution
-Guidelines](https://docs.syncthing.net/dev/contributing.html) for the full
-story on committing code.
-
 ## Contributing Documentation
 
 Updates to the [documentation site](https://docs.syncthing.net/) can be
 made as pull requests on the [documentation
 repository](https://github.com/syncthing/docs).
 
+## Contributing Code
+
+Every contribution is welcome. If you want to contribute but are unsure
+where to start, any open issues are fair game! Here's a short rundown of
+what you need to keep in mind:
+
+- Don't worry. You are not expected to get everything right on the first
+  attempt, we'll guide you through it.
+
+- Make sure there is an
+  [issue](https://github.com/syncthing/syncthing/issues) that describes the
+  change you want to do. If the thing you want to do does not have an issue
+  yet, please file one before starting work on it.
+
+- Fork the repository and make your changes in a new branch. Once it's ready
+  for review, create a pull request.
+
+### Authorship
+
+All code authors are listed in the AUTHORS file. When your first pull
+request is accepted your details are added to the AUTHORS file and the list
+of authors in the GUI. Commits must be made with the same name and email as
+listed in the AUTHORS file. To accomplish this, ensure that your git
+configuration is set correctly prior to making your first commit:
+
+    $ git config --global user.name "Jane Doe"
+    $ git config --global user.email janedoe@example.com
+
+You must be reachable on the given email address. If you do not wish to use
+your real name for whatever reason, using a nickname or pseudonym is
+perfectly acceptable.
+
+### The Developer Certificate of Origin (DCO)
+
+The Syncthing project requires the Developer Certificate of Origin (DCO)
+sign-off on pull requests (PRs). This means that all commit messages must
+contain a signature line to indicate that the developer accepts the DCO.
+
+The DCO is a lightweight way for contributors to certify that they wrote (or
+otherwise have the right to submit) the code and changes they are
+contributing to the project. Here is the full [text of the
+DCO](https://developercertificate.org):
+
+---
+
+By making a contribution to this project, I certify that:
+
+1. The contribution was created in whole or in part by me and I have the
+   right to submit it under the open source license indicated in the file;
+   or
+
+2. The contribution is based upon previous work that, to the best of my
+   knowledge, is covered under an appropriate open source license and I have
+   the right under that license to submit that work with modifications,
+   whether created in whole or in part by me, under the same open source
+   license (unless I am permitted to submit under a different license), as
+   indicated in the file; or
+
+3. The contribution was provided directly to me by some other person who
+   certified (1), (2) or (3) and I have not modified it.
+
+4. I understand and agree that this project and the contribution are public
+   and that a record of the contribution (including all personal information
+   I submit with it, including my sign-off) is maintained indefinitely and
+   may be redistributed consistent with this project or the open source
+   license(s) involved.
+
+---
+
+Contributors indicate that they adhere to these requirements by adding
+a `Signed-off-by` line to their commit messages.  For example:
+
+    This is my commit message
+
+    Signed-off-by: Random J Developer <random@developer.example.org>
+
+The name and email address in this line must match those of the committing
+author, and be the same as what you want in the AUTHORS file as per above.
+
+### Coding Style
+
+#### General
+
+- All text files use Unix line endings. The git settings already present in
+  the repository attempt to enforce this.
+
+- When making changes, follow the brace and parenthesis style of the
+  surrounding code.
+
+#### Go Specific
+
+- Follow the conventions laid out in [Effective
+  Go](https://go.dev/doc/effective_go) as much as makes sense. The review
+  guidelines in [Go Code Review
+  Comments](https://github.com/golang/go/wiki/CodeReviewComments) should
+  generally be followed.
+
+- Each commit should be `go fmt` clean.
+
+- Imports are grouped per `goimports` standard; that is, standard
+  library first, then third party libraries after a blank line.
+
+### Commits
+
+- Commit messages (and pull request titles) should follow the [conventional
+  commits](https://www.conventionalcommits.org/en/v1.0.0/) specification and
+  be in lower case.
+
+- We use a scope description in the commit message subject. This is the
+  component of Syncthing that the commit affects. For example, `gui`,
+  `protocol`, `scanner`, `upnp`, etc -- typically, the part after
+  `internal/`, `lib/` or `cmd/` in the package path. If the commit doesn't
+  affect a specific component, such as for changes to the build system or
+  documentation, the scope should be omitted. The same goes for changes that
+  affect many components which would be cumbersome to list.
+
+- Commits that resolve an existing issue must include the issue number
+  as `(fixes #123)` at the end of the commit message subject. A correctly
+  formatted commit message subject looks like this:
+
+      feat(dialer): add env var to disable proxy fallback (fixes #3006)
+
+- If the commit message subject doesn't say it all, one or more paragraphs of
+  describing text should be added to the commit message. This should explain
+  why the change is made and what it accomplishes.
+
+- When drafting a pull request, please feel free to add commits with
+  corrections and merge from `main` when necessary. This provides a clear time
+  line with changes and simplifies review. Do not, in general, rebase your
+  commits, as this makes review harder.
+
+- Pull requests are merged to `main` using squash merge. The "stream of
+  consciousness" set of commits described in the previous point will be reduced
+  to a single commit at merge time. The pull request title and description will
+  be used as the commit message.
+
+### Tests
+
+Yes please, do add tests when adding features or fixing bugs. Also, when a
+pull request is filed a number of automatic tests are run on the code. This
+includes:
+
+- That the code actually builds and the test suite passes.
+
+- That the code is correctly formatted (`go fmt`).
+
+- That the commits are based on a reasonably recent `main`.
+
+- That the output from `go lint` and `go vet` is clean. (This checks for a
+  number of potential problems the compiler doesn't catch.)
+
 ## Licensing
 
 All contributions are made available under the same license as the already
@@ -59,10 +203,6 @@ otherwise stated this means MPLv2, but there are exceptions:
 - The documentation (man/...) is licensed under the Creative Commons
   Attribution 4.0 International License.
 
-- Projects under vendor/... are copyright by and licensed from their
-  respective original authors. Contributions should be made to the original
-  project, not here.
-
 Regardless of the license in effect, you retain the copyright to your
 contribution.
 

cmd/syncthing/perfstats_unix.go

@@ -16,6 +16,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/locations"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"golang.org/x/exp/constraints"
@@ -48,11 +49,16 @@ func savePerfStats(file string) {
 		in, out := protocol.TotalInOut()
 		timeDiff := t.Sub(prevTime)
 
+		rss := curRus.Maxrss
+		if build.IsDarwin {
+			rss /= 1024
+		}
+
 		fmt.Fprintf(fd, "%.03f\t%f\t%d\t%d\t%.0f\t%.0f\t%d\n",
 			t.Sub(t0).Seconds(),
 			rate(cpusec(&prevRus), cpusec(&curRus), timeDiff, 1),
 			(curMem.Sys-curMem.HeapReleased)/1024,
-			curRus.Maxrss/1024,
+			rss,
 			rate(prevIn, in, timeDiff, 1e3),
 			rate(prevOut, out, timeDiff, 1e3),
 			dirsize(locations.Get(locations.Database))/1024,

internal/db/sqlite/basedb.go

@@ -110,6 +110,7 @@ func openBase(path string, maxConns int, pragmas, schemaScripts, migrationScript
 			}
 			if int(n) > ver.SchemaVersion {
 				slog.Info("Applying database migration", slogutil.FilePath(db.baseName), slog.String("script", scr))
+				shouldVacuum = true
 				return true
 			}
 			return false
@@ -118,7 +119,6 @@ func openBase(path string, maxConns int, pragmas, schemaScripts, migrationScript
 			if err := db.runScripts(tx, script, filter); err != nil {
 				return nil, wrap(err)
 			}
-			shouldVacuum = true
 		}
 	}
 

internal/db/sqlite/db_open.go

@@ -52,8 +52,6 @@ func Open(path string, opts ...Option) (*DB, error) {
 		"journal_mode = WAL",
 		"optimize = 0x10002",
 		"auto_vacuum = INCREMENTAL",
-		"default_temp_store = MEMORY",
-		"temp_store = MEMORY",
 	}
 	schemas := []string{
 		"sql/schema/common/*",
@@ -99,8 +97,6 @@ func Open(path string, opts ...Option) (*DB, error) {
 func OpenForMigration(path string) (*DB, error) {
 	pragmas := []string{
 		"journal_mode = OFF",
-		"default_temp_store = MEMORY",
-		"temp_store = MEMORY",
 		"foreign_keys = 0",
 		"synchronous = 0",
 		"locking_mode = EXCLUSIVE",

internal/db/sqlite/folderdb_open.go

@@ -25,8 +25,6 @@ func openFolderDB(folder, path string, deleteRetention time.Duration) (*folderDB
 		"journal_mode = WAL",
 		"optimize = 0x10002",
 		"auto_vacuum = INCREMENTAL",
-		"default_temp_store = MEMORY",
-		"temp_store = MEMORY",
 	}
 	schemas := []string{
 		"sql/schema/common/*",
@@ -64,8 +62,6 @@ func openFolderDB(folder, path string, deleteRetention time.Duration) (*folderDB
 func openFolderDBForMigration(folder, path string, deleteRetention time.Duration) (*folderDB, error) {
 	pragmas := []string{
 		"journal_mode = OFF",
-		"default_temp_store = MEMORY",
-		"temp_store = MEMORY",
 		"foreign_keys = 0",
 		"synchronous = 0",
 		"locking_mode = EXCLUSIVE",