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perf: optimize pg describe tables query #147

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perf: optimize pg describe tables query #147

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169 changes: 68 additions & 101 deletions internal/database/postgresql.go
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Original file line number Diff line number Diff line change
Expand Up @@ -221,111 +221,78 @@ func (db *PostgreSQLDBRepository) Tables(ctx context.Context) ([]string, error)
}

func (db *PostgreSQLDBRepository) DescribeDatabaseTable(ctx context.Context) ([]*ColumnDesc, error) {
rows, err := db.Conn.QueryContext(
ctx,
`
SELECT
c.table_schema,
c.table_name,
c.column_name,
c.data_type,
c.is_nullable,
CASE t.constraint_type
WHEN 'PRIMARY KEY' THEN 'YES'
ELSE 'NO'
END,
c.column_default,
''
FROM
information_schema.columns c
LEFT JOIN (
SELECT
ccu.table_schema as table_schema,
ccu.table_name as table_name,
ccu.column_name as column_name,
tc.constraint_type as constraint_type
FROM information_schema.constraint_column_usage ccu
LEFT JOIN information_schema.table_constraints tc ON
tc.table_schema = ccu.table_schema
AND tc.table_name = ccu.table_name
AND tc.constraint_name = ccu.constraint_name
WHERE
tc.constraint_type = 'PRIMARY KEY'
) as t
ON c.table_schema = t.table_schema
AND c.table_name = t.table_name
AND c.column_name = t.column_name
ORDER BY
c.table_name,
c.ordinal_position
`)
if err != nil {
log.Fatal(err)
}
defer rows.Close()
tableInfos := []*ColumnDesc{}
for rows.Next() {
var tableInfo ColumnDesc
err := rows.Scan(
&tableInfo.Schema,
&tableInfo.Table,
&tableInfo.Name,
&tableInfo.Type,
&tableInfo.Null,
&tableInfo.Key,
&tableInfo.Default,
&tableInfo.Extra,
)
if err != nil {
return nil, err
}
tableInfos = append(tableInfos, &tableInfo)
}
return tableInfos, nil
return db.DescribeDatabaseTableBySchema(ctx, "")
}

func (db *PostgreSQLDBRepository) DescribeDatabaseTableBySchema(ctx context.Context, schemaName string) ([]*ColumnDesc, error) {
rows, err := db.Conn.QueryContext(
ctx,
var parameters []interface{}
var query strings.Builder

query.WriteString(
`
SELECT
c.table_schema,
c.table_name,
c.column_name,
c.data_type,
c.is_nullable,
CASE t.constraint_type
WHEN 'PRIMARY KEY' THEN 'YES'
ELSE 'NO'
END,
c.column_default,
''
FROM
information_schema.columns c
LEFT JOIN (
SELECT
ccu.table_schema as table_schema,
ccu.table_name as table_name,
ccu.column_name as column_name,
tc.constraint_type as constraint_type
FROM information_schema.constraint_column_usage ccu
LEFT JOIN information_schema.table_constraints tc ON
tc.table_schema = ccu.table_schema
AND tc.table_name = ccu.table_name
AND tc.constraint_name = ccu.constraint_name
WHERE
ccu.table_schema = $1
AND tc.constraint_type = 'PRIMARY KEY'
) as t
ON c.table_schema = t.table_schema
AND c.table_name = t.table_name
AND c.column_name = t.column_name
WHERE
c.table_schema = $2
ORDER BY
c.table_name,
c.ordinal_position
`, schemaName, schemaName)
SELECT DISTINCT ON (table_schema, table_name, a.attnum)
c1.relnamespace::regnamespace AS table_schema, c1.relname AS table_name, a.attname AS column_name, CASE WHEN
t.typtype = 'd'::"char" THEN
CASE WHEN bt.typelem <> 0::oid
AND bt.typlen = '-1'::integer THEN
'ARRAY'::text
WHEN nbt.nspname = 'pg_catalog'::name THEN
format_type(t.typbasetype, NULL::integer)
ELSE
'USER-DEFINED'::text
END
ELSE
CASE WHEN t.typelem <> 0::oid
AND t.typlen = '-1'::integer THEN
'ARRAY'::text
WHEN nt.nspname = 'pg_catalog'::name THEN
format_type(a.atttypid, NULL::integer)
ELSE
'USER-DEFINED'::text
END
END::information_schema.character_data AS data_type, CASE WHEN a.attnotnull
OR t.typtype = 'd'::"char"
AND t.typnotnull THEN
'NO'::text
ELSE
'YES'::text
END::information_schema.yes_or_no AS is_nullable, CASE WHEN conn.contype = 'p' THEN
'YES'
ELSE
'NO'
END AS is_primary_key, CASE WHEN a.attgenerated = ''::"char" THEN
pg_get_expr(ad.adbin, ad.adrelid)
ELSE
NULL::text
END::information_schema.character_data AS column_default, ''
FROM pg_catalog.pg_class c1
JOIN pg_catalog.pg_attribute a ON a.attrelid = c1.oid
JOIN (pg_type t
JOIN pg_namespace nt ON t.typnamespace = nt.oid) ON a.atttypid = t.oid
LEFT JOIN (pg_type bt
JOIN pg_namespace nbt ON bt.typnamespace = nbt.oid) ON t.typtype = 'd'::char
AND t.typbasetype = bt.oid
LEFT JOIN pg_catalog.pg_constraint conn ON conn.conrelid = c1.oid
AND a.attnum = ANY (conn.conkey)
AND conn.contype = 'p'
LEFT JOIN pg_attrdef ad ON a.attrelid = ad.adrelid
AND a.attnum = ad.adnum
WHERE c1.relkind = ANY (ARRAY['p', 'r', 'v'])
AND a.attnum > 0
AND (pg_has_role(c1.relowner, 'USAGE'::text)
OR has_column_privilege(c1.oid, a.attnum, 'SELECT, INSERT, UPDATE, REFERENCES'::text))
`,
)

if (schemaName != "") {
parameters = append(parameters, schemaName)
query.WriteString(`
AND c1.relnamespace = $1::regnamespace::oid
`)
}

query.WriteString("ORDER BY table_name, a.attnum")
rows, err := db.Conn.QueryContext( ctx, query.String(), parameters...)
if err != nil {
log.Fatal(err)
}
Expand Down