comprules: support completion for qualified functions

The syntax completion engine now generates suggestion for user-defined
functions. It restricts the suggestions to only functions in the schema
name if one was provided, or else to the schemas in the search_path.

No release note since this functionality is new in v23.1.

Release note: None

pkg/ccl/logictestccl/testdata/logic_test/crdb_internal_tenant

@@ -261,10 +261,10 @@ SELECT * FROM crdb_internal.cluster_contention_events WHERE table_id < 0
 ----
 table_id  index_id  num_contention_events  cumulative_contention_time  key  txn_id  count
 
-query TTTT colnames
+query TTTTT colnames
 SELECT * FROM crdb_internal.builtin_functions WHERE function = ''
 ----
-function  signature  category  details
+function  signature  category  details  schema
 
 query ITTITTTTTTTBBBB colnames
 SELECT * FROM crdb_internal.create_statements WHERE database_name = ''

pkg/cli/clisqlshell/sql.go

@@ -1326,7 +1326,22 @@ func (c *cliState) doHandleCliCmd(loopState, nextState cliStateEnum) cliStateEnu
 
 	case `\hf`:
 		if len(cmd) == 1 {
-			c.concatLines = `SELECT DISTINCT proname AS function FROM pg_proc ORDER BY 1`
+			// The following query lists all functions. It prefixes
+			// functions with their schema but only if the schema is not in
+			// the search path. This ensures that "common" functions
+			// are not prefixed by "pg_catalog", but crdb_internal functions
+			// get prefixed with "crdb_internal."
+			//
+			// TODO(knz): Replace this by the \df logic when that is implemented;
+			// see: https://github.com/cockroachdb/cockroach/pull/88061
+			c.concatLines = `
+SELECT DISTINCT
+       IF(n.nspname = ANY current_schemas(TRUE), '',
+          pg_catalog.quote_ident(n.nspname) || '.') ||
+       pg_catalog.quote_ident(p.proname) AS function
+  FROM pg_catalog.pg_proc p
+  JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace
+ORDER BY 1`
 			return cliRunStatement
 		}
 		return c.handleFunctionHelp(cmd[1:], loopState, errState)

pkg/cli/clisqlshell/testdata/complete/composite_names

@@ -11,3 +11,55 @@ msg: ""
 completions:
 - "functions":
   "crdb_internal.force_error(" (This function is used only by CockroachDB's developers for testing purposes.) -> "crdb_internal.force_error(" (0, 25)
+
+sql
+create schema my_schema
+----
+ok
+
+sql
+CREATE FUNCTION my_func(i INT) RETURNS INT LANGUAGE SQL AS 'SELECT i'
+----
+ok
+
+sql
+CREATE FUNCTION my_schema.my_other_func(i INT) RETURNS INT LANGUAGE SQL AS 'SELECT i'
+----
+ok
+
+complete
+select my@
+----
+complete 0 9
+msg: ""
+completions:
+- "functions":
+  "my_func(" () -> "my_func(" (0, 2)
+- "schema":
+  "my_schema" () -> "my_schema" (0, 2)
+
+complete
+select my_schema.@
+----
+complete 0 17
+msg: ""
+completions:
+- "functions":
+  "my_schema.my_other_func(" () -> "my_schema.my_other_func(" (0, 10)
+
+complete
+select pg_catalog.array_l@
+----
+complete 0 25
+msg: ""
+completions:
+- "functions":
+  "pg_catalog.array_length(" (Calculates the length of `input` on the provided `array_dimension`. However, bec) -> "pg_catalog.array_length(" (0, 18)
+  "pg_catalog.array_lower(" (Calculates the minimum value of `input` on the provided `array_dimension`. Howev) -> "pg_catalog.array_lower(" (0, 18)
+
+complete
+select "PG_CATALOG".@
+----
+complete 0 20
+msg: ""
+(no completions generated)

pkg/cli/clisqlshell/testdata/complete/sql

@@ -102,3 +102,13 @@ msg: ""
 completions:
 - "relation":
   "mytable" () -> "mytable" (0, 0)
+
+complete
+select array_l@
+----
+complete 0 14
+msg: ""
+completions:
+- "functions":
+  "array_length(" (Calculates the length of `input` on the provided `array_dimension`. However, bec) -> "array_length(" (0, 7)
+  "array_lower(" (Calculates the minimum value of `input` on the provided `array_dimension`. Howev) -> "array_lower(" (0, 7)

pkg/sql/comprules/rules.go

@@ -25,7 +25,7 @@ import (
 func GetCompMethods() []compengine.Method {
 	return []compengine.Method{
 		method("keywords", completeKeyword),
-		method("builtins", completeBuiltin),
+		method("functions", completeFunction),
 		method("objects", completeObjectInCurrentDatabase),
 		method("schemas", completeSchemaInCurrentDatabase),
 		method("dbs", completeDatabase),
@@ -96,41 +96,27 @@ var compNotQualProcRe = regexp.MustCompile(`[^.](i'|_)`)
 // A qualified possible builtin name.
 var compMaybeQualProcRe = regexp.MustCompile(`i\.['_]|i\.i'`)
 
-var compVSchemaRe = regexp.MustCompile(`pg_catalog|crdb_internal|information_schema`)
-
-func completeBuiltin(ctx context.Context, c compengine.Context) (compengine.Rows, error) {
-	// Complete builtin names:
+func completeFunction(ctx context.Context, c compengine.Context) (compengine.Rows, error) {
+	// Complete function names:
 	//
 	// - at whitespace after keywords.
-	// - after a period, if the identifier before the period is a vschema.
+	// - after a period.
 	//
 	var prefix string
 	var start, end int
-	var extraPrefix string
+	var schemaName string
 	atWord := c.AtWord()
 	sketch := c.Sketch()
 	switch {
-	case compMaybeQualProcRe.MatchString(sketch) &&
-		((!atWord && compVSchemaRe.MatchString(c.RelToken(-1).Str)) ||
-			(atWord && compVSchemaRe.MatchString(c.RelToken(-2).Str))):
+	case compMaybeQualProcRe.MatchString(sketch):
 		start = int(c.RelToken(-1).Start)
-		prefix = c.RelToken(-1).Str + "."
+		schemaName = c.RelToken(-1).Str
 		if atWord {
 			start = int(c.RelToken(-2).Start)
-			prefix = c.RelToken(-2).Str + "."
-		}
-		// crdb has this weird thing where every unqualified built-in "X"
-		// also exists as "pg_catalog.X". So when we search for
-		// completions after "pg_catalog.", we can strip that prefix from
-		// the search. However, we must be careful to add it back in the
-		// completion results, so that the prefix does not get stripped
-		// when the completion occurs.
-		if prefix == "pg_catalog." {
-			prefix = ""
-			extraPrefix = "pg_catalog."
+			schemaName = c.RelToken(-2).Str
 		}
 		if atWord {
-			prefix += c.RelToken(0).Str
+			prefix = c.RelToken(0).Str
 		}
 		end = int(c.RelToken(0).End)
 
@@ -152,23 +138,31 @@ func completeBuiltin(ctx context.Context, c compengine.Context) (compengine.Rows
 		return nil, nil
 	}
 
-	c.Trace("completing for %q (%d,%d)", prefix, start, end)
+	c.Trace("completing for %q (%d,%d) with schema %q", prefix, start, end, schemaName)
 	// TODO(knz): use the comment extraction functions from pg_catalog
 	// instead of crdb_internal. This requires exposing comments for
 	// built-in functions through pg_catalog.
 	const query = `
-WITH p AS (SELECT DISTINCT proname FROM pg_catalog.pg_proc)
-SELECT $4:::STRING || proname || '(' AS completion,
+WITH p AS (
+SELECT DISTINCT
+       proname, nspname
+  FROM pg_catalog.pg_proc
+  JOIN pg_catalog.pg_namespace n ON n.oid = pronamespace)
+SELECT IF(length($4) > 0, pg_catalog.quote_ident($4:::STRING) || '.', '') ||
+       pg_catalog.quote_ident(proname) || '(' AS completion,
        'functions' AS category,
-       substr(COALESCE((SELECT details
+       substr(COALESCE((
+         SELECT details
           FROM "".crdb_internal.builtin_functions f2
-         WHERE f2.function = p.proname
+         WHERE f2.function = p.proname AND f2.schema = p.nspname
          LIMIT 1), ''), e'[^\n]{0,80}') AS description,
        $2:::INT AS start,
        $3:::INT AS end
   FROM p
- WHERE left(proname, length($1:::STRING)) = $1:::STRING`
-	iter, err := c.Query(ctx, query, prefix, start, end, extraPrefix)
+ WHERE left(proname, length($1:::STRING)) = $1:::STRING
+ AND ((length($4) > 0 AND $4 = nspname)
+   OR (length($4) = 0 AND nspname = ANY current_schemas(true)))`
+	iter, err := c.Query(ctx, query, prefix, start, end, schemaName)
 	return iter, err
 }