Jack Christensen
7de53a958b
Statement names are now a function of the SQL. This may make database diagnostics, monitoring, and profiling easier.
57 lines
1.9 KiB
Go
57 lines
1.9 KiB
Go
// Package stmtcache is a cache for statement descriptions.
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package stmtcache
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import (
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"crypto/sha256"
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"encoding/hex"
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"github.com/jackc/pgx/v5/pgconn"
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)
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// StatementName returns a statement name that will be stable for sql across multiple connections and program
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// executions.
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func StatementName(sql string) string {
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digest := sha256.Sum256([]byte(sql))
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return "stmtcache_" + hex.EncodeToString(digest[0:24])
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}
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// Cache caches statement descriptions.
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type Cache interface {
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// Get returns the statement description for sql. Returns nil if not found.
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Get(sql string) *pgconn.StatementDescription
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// Put stores sd in the cache. Put panics if sd.SQL is "". Put does nothing if sd.SQL already exists in the cache.
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Put(sd *pgconn.StatementDescription)
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// Invalidate invalidates statement description identified by sql. Does nothing if not found.
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Invalidate(sql string)
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// InvalidateAll invalidates all statement descriptions.
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InvalidateAll()
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// HandleInvalidated returns a slice of all statement descriptions invalidated since the last call to HandleInvalidated.
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HandleInvalidated() []*pgconn.StatementDescription
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// Len returns the number of cached prepared statement descriptions.
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Len() int
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// Cap returns the maximum number of cached prepared statement descriptions.
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Cap() int
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}
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func IsStatementInvalid(err error) bool {
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pgErr, ok := err.(*pgconn.PgError)
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if !ok {
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return false
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}
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// https://github.com/jackc/pgx/issues/1162
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//
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// We used to look for the message "cached plan must not change result type". However, that message can be localized.
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// Unfortunately, error code "0A000" - "FEATURE NOT SUPPORTED" is used for many different errors and the only way to
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// tell the difference is by the message. But all that happens is we clear a statement that we otherwise wouldn't
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// have so it should be safe.
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possibleInvalidCachedPlanError := pgErr.Code == "0A000"
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return possibleInvalidCachedPlanError
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}
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