sql: allow inverted indexes on mixed-case cols

Previously, a bug prevented creation of inverted indexes on columns with
mixed-case identifiers. Now, the bug is fixed.

Release note (bug fix): it is now possible to create inverted indexes on
columns whose names are mixed-case.

pkg/sql/backfill.go

@@ -1243,7 +1243,7 @@ func (sc *SchemaChanger) validateInvertedIndexes(
 				row, err := ie.QueryRowEx(ctx, "verify-inverted-idx-count", txn,
 					sqlbase.InternalExecutorSessionDataOverride{},
 					fmt.Sprintf(
-						`SELECT coalesce(sum_int(crdb_internal.json_num_index_entries(%s)), 0) FROM [%d AS t]`,
+						`SELECT coalesce(sum_int(crdb_internal.json_num_index_entries(%q)), 0) FROM [%d AS t]`,
 						col, tableDesc.ID,
 					),
 				)

pkg/sql/logictest/testdata/logic_test/inverted_index

@@ -26,10 +26,11 @@ statement ok
 CREATE TABLE c (
   id INT PRIMARY KEY,
   foo JSON,
-  bar JSON,
+  "bAr" JSON,
+  "qUuX" JSON,
   INVERTED INDEX (foo),
-  INVERTED INDEX (bar),
-  FAMILY "primary" (id, foo, bar)
+  INVERTED INDEX ("bAr"),
+  FAMILY "primary" (id, foo, "bAr", "qUuX")
 )
 
 query TT
@@ -38,13 +39,19 @@ SHOW CREATE TABLE c
 c  CREATE TABLE c (
    id INT8 NOT NULL,
    foo JSONB NULL,
-   bar JSONB NULL,
+   "bAr" JSONB NULL,
+   "qUuX" JSONB NULL,
    CONSTRAINT "primary" PRIMARY KEY (id ASC),
    INVERTED INDEX c_foo_idx (foo),
-   INVERTED INDEX c_bar_idx (bar),
-   FAMILY "primary" (id, foo, bar)
+   INVERTED INDEX "c_bAr_idx" ("bAr"),
+   FAMILY "primary" (id, foo, "bAr", "qUuX")
 )
 
+# Regression test for #42944: make sure that mixed-case columns can be
+# inverted indexed.
+statement ok
+CREATE INVERTED INDEX ON c("qUuX")
+
 statement error indexing more than one column with an inverted index is not supported
 CREATE TABLE d (
   id INT PRIMARY KEY,