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Disable synchronous_commit by default for writer connections
Disabling synchronous_commit for the database connections in the writer pool will improve performance. The tradeoff is that some amount of writes may be lost in the event of a crash. This is likely an "okay" tradeoff for monitoring data. By default, we now disable synchronous_commit at the session level on connections in the writer pool. This does not impact other connections/sessions. A new config option has been added to override this default.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,77 @@ | ||
| package end_to_end_tests | ||
|
|
||
| import ( | ||
| "context" | ||
| "testing" | ||
|
|
||
| "github.com/jackc/pgx/v4" | ||
| "github.com/jackc/pgx/v4/pgxpool" | ||
| "github.com/stretchr/testify/require" | ||
| "github.com/timescale/promscale/pkg/pgclient" | ||
| ) | ||
|
|
||
| /// TestWriterSynchronousCommit ensures that the database pool for the writer can be configured with synchronous_commit | ||
| /// turned on or off and that the effects are limited to that pool | ||
| func TestWriterSynchronousCommit(t *testing.T) { | ||
|
|
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| // creates a new pool of database connections as would be created for the writer path | ||
| createWriterPool := func(connStr string, lockerCalled *bool, synchronousCommit bool) *pgxpool.Pool { | ||
| pgConfig, err := pgxpool.ParseConfig(connStr) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| pgConfig.MaxConns = 2 | ||
| pgConfig.MinConns = 1 | ||
| *lockerCalled = false | ||
| schemaLocker := func(ctx context.Context, conn *pgx.Conn) error { | ||
| *lockerCalled = true | ||
| return nil | ||
| } | ||
| pgclient.SetWriterPoolAfterConnect(pgConfig, schemaLocker, synchronousCommit) | ||
| writerPool, err := pgxpool.ConnectConfig(context.Background(), pgConfig) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| return writerPool | ||
| } | ||
|
|
||
| // gets the value of the synchronous_commit setting from the database | ||
| getSynchronousCommit := func(writerPool *pgxpool.Pool) string { | ||
| var setting string | ||
| err := writerPool.QueryRow(context.Background(), "show synchronous_commit").Scan(&setting) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| return setting | ||
| } | ||
|
|
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| withDB(t, "writer_sync_commit", func(db *pgxpool.Pool, t testing.TB) { | ||
| var lockerCalled bool // used to ensure that the schema locker function is still called | ||
|
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| // create a writer pool with synchronous_commit turned off | ||
| writerPool1 := createWriterPool(db.Config().ConnString(), &lockerCalled, false) | ||
| setting := getSynchronousCommit(writerPool1) | ||
| require.Equal(t, "off", setting, "expected synchronous_commit to be off but it was %s", setting) | ||
| require.True(t, lockerCalled, "schemaLocker function should have been called and wasn't") | ||
|
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| // ensure that setting synchronous_commit to off on the writer pool did not impact the setting | ||
| // in other database sessions | ||
| setting = getSynchronousCommit(db) | ||
| require.Equal(t, "on", setting, "expected synchronous_commit to be on but it was %s", setting) | ||
|
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| // make sure the setting stays off after the first transaction finished | ||
| setting = getSynchronousCommit(writerPool1) | ||
| require.Equal(t, "off", setting, "expected synchronous_commit to be off but it was %s", setting) | ||
| writerPool1.Close() | ||
|
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| // now create a writer pool with synchronous_commit turned on | ||
| lockerCalled = false | ||
| writerPool2 := createWriterPool(db.Config().ConnString(), &lockerCalled, true) | ||
|
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| // make sure the setting is on and the schema locker function was called | ||
| setting = getSynchronousCommit(writerPool2) | ||
| require.Equal(t, "on", setting, "expected synchronous_commit to be on but it was %s", setting) | ||
| require.True(t, lockerCalled, "schemaLocker function should have been called and wasn't") | ||
| writerPool2.Close() | ||
| }) | ||
| } |