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Merge pull request #336 from Quentin-M/master

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Use a Size() estimate for SQL Quadstore when noSizes is enabled.
This commit is contained in:
Barak Michener 2015-11-16 22:11:01 +01:00
commit 6027e4c48b
1 changed files with 23 additions and 6 deletions
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19
graph/sql/quadstore.go
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@ -42,6 +42,7 @@ type QuadStore struct {
size int64 size int64
lru *cache lru *cache
noSizes bool noSizes bool
useEstimates bool
} }
func connectSQLTables(addr string, _ graph.Options) (*sql.DB, error) { func connectSQLTables(addr string, _ graph.Options) (*sql.DB, error) {
@ -132,6 +133,11 @@ func newQuadStore(addr string, options graph.Options) (graph.QuadStore, error) {
qs.noSizes = false qs.noSizes = false
} }
} }
qs.useEstimates, _, err = options.BoolKey("use_estimates")
if err != nil {
return nil, err
}
return &qs, nil return &qs, nil
} }
@ -286,7 +292,18 @@ func (qs *QuadStore) Size() int64 {
if qs.size != -1 { if qs.size != -1 {
return qs.size return qs.size
} }
c := qs.db.QueryRow("SELECT COUNT(*) FROM quads;")
query := "SELECT COUNT(*) FROM quads;"
if qs.useEstimates {
switch qs.sqlFlavor {
case "postgres":
query = "SELECT reltuples::BIGINT AS estimate FROM pg_class WHERE relname='quads';"
default:
panic("no estimate support for flavor: " + qs.sqlFlavor)
}
}
c := qs.db.QueryRow(query)
err := c.Scan(&qs.size) err := c.Scan(&qs.size)
if err != nil { if err != nil {
glog.Errorf("Couldn't execute COUNT: %v", err) glog.Errorf("Couldn't execute COUNT: %v", err)