Outline digest match fails with EXPLAIN ANALYZE

[kaiwangchen]

-- ind_1 was chosen without outline
CALL dbms_outln.add_index_outline('outline_db', '', 1, 'USE INDEX', 'ind_2', '',
"select * from t1 where t1.col1 =1 and t1.col2 ='xpchild'");
EXPLAIN FORMAT = tree SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
EXPLAIN
-> Filter: (t1.col1 = 2)  (cost=0.35 rows=1)
    -> Index lookup on t1 using ind_2 (col2='xpchild')  (cost=0.35 rows=1)

EXPLAIN ANALYZE SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
EXPLAIN
-> Filter: (t1.col2 = 'xpchild')  (cost=0.35 rows=1) (actual time=0.016..0.017 rows=1 loops=1)
    -> Index lookup on t1 using ind_1 (col1=2)  (cost=0.35 rows=1) (actual time=0.014..0.016 rows=1 loops=1)

[kaiwangchen]

diff --git a/mysql-test/suite/galaxy_sql/r/feature_outline.result b/mysql-test/suite/galaxy_sql/r/feature_outline.result
index 75dbd183931..0ecde35091d 100644
--- a/mysql-test/suite/galaxy_sql/r/feature_outline.result
+++ b/mysql-test/suite/galaxy_sql/r/feature_outline.result
@@ -541,6 +541,26 @@ id select_type     table   partitions      type    possible_keys   key     key_len ref     rows    filtered
 1      SIMPLE  t1      NULL    ref     ind_1   ind_1   5       const   1       100.00  Using where
 Warnings:
 Note   1003    /* select#1 */ select `outline_db`.`t1`.`id` AS `id`,`outline_db`.`t1`.`col1` AS `col1`,`outline_db`.`t1`.`col2` AS `col2` from `outline_db`.`t1` USE INDEX (`ind_1`) where ((`outline_db`.`t1`.`col2` = 'xpchild') and (`outline_db`.`t1`.`col1` = 2))
+delete from mysql.outline;
+commit;
+call dbms_outln.flush_outline();
+CALL dbms_outln.add_index_outline('outline_db', '', 1, 'USE INDEX', 'ind_2', '',
+"select * from t1 where t1.col1 =1 and t1.col2 ='xpchild'");
+EXPLAIN FORMAT = tree SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
+EXPLAIN
+-> Filter: (t1.col1 = 2)  (cost=0.35 rows=1)
+    -> Index lookup on t1 using ind_2 (col2='xpchild')  (cost=0.35 rows=1)
+
+EXPLAIN ANALYZE SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
+EXPLAIN
+-> Filter: (t1.col1 = 2)  (cost=0.35 rows=1) (actual time=0.033..0.035 rows=1 loops=1)
+    -> Index lookup on t1 using ind_2 (col2='xpchild')  (cost=0.35 rows=1) (actual time=0.031..0.033 rows=1 loops=1)
+
+EXPLAIN ANALYZE FORMAT=tree SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
+EXPLAIN
+-> Filter: (t1.col1 = 2)  (cost=0.35 rows=1) (actual time=0.024..0.027 rows=1 loops=1)
+    -> Index lookup on t1 using ind_2 (col2='xpchild')  (cost=0.35 rows=1) (actual time=0.023..0.025 rows=1 loops=1)
+
 delete from mysql.outline;
 commit;
 call dbms_outln.flush_outline();
diff --git a/mysql-test/suite/galaxy_sql/t/feature_outline.test b/mysql-test/suite/galaxy_sql/t/feature_outline.test
index a999d7dee12..c5f3fddf240 100644
--- a/mysql-test/suite/galaxy_sql/t/feature_outline.test
+++ b/mysql-test/suite/galaxy_sql/t/feature_outline.test
@@ -452,6 +452,15 @@ EXPLAIN FORMAT = TRADITIONAL SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpc
 EXPLAIN FORMAT = 'JsOn' SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
 EXPLAIN FORMAT = 'TrAdItIoNaL' SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
 
+delete from mysql.outline;
+commit;
+call dbms_outln.flush_outline();
+
+CALL dbms_outln.add_index_outline('outline_db', '', 1, 'USE INDEX', 'ind_2', '',
+                                "select * from t1 where t1.col1 =1 and t1.col2 ='xpchild'");
+EXPLAIN FORMAT = tree SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
+EXPLAIN ANALYZE SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
+EXPLAIN ANALYZE FORMAT=tree SELECT * FROM t1 WHERE t1.col1 =2 AND t1.col2 ='xpchild';
 
 delete from mysql.outline;
 commit;
diff --git a/sql/outline/outline_digest.cc b/sql/outline/outline_digest.cc
index 277763d47fd..dede6dbd4d1 100644
--- a/sql/outline/outline_digest.cc
+++ b/sql/outline/outline_digest.cc
@@ -31,18 +31,24 @@
 
 namespace im {
 
-#define EXPLAIN_TOKEN_SIZE 2
-#define EXPLAIN_FORMAT_MINIMAL_LENGTH 6
-#define IDENT_LENGTH_SIZE 2
-#define LEAST_TOKEN_SIZE 2
+#define SIZE_OF_A_TOKEN 2
+#define GET_TOKEN(p) (*(p) | (*(p+1) << 8))
+// The shortest valid real query should be "SELECT 1".
+#define EXPLAIN_QUERY_MININUM_LENGTH 4
+// param=value
+#define EXPLAIN_PARAM_MINIMAL_LENGTH 6
+#define ASSERT_LENGTH(len) \
+  assert(p + (len) + EXPLAIN_QUERY_MININUM_LENGTH <= end)
 
 /**
   Calculate the offset of the real query in the digest storage.
 
   The digesting process converts a SQL statement to normalized form by
   translating each token to a few digest bytes. This function calculates the
-  number of bytes that should be stripped to skip the digest bytes corresponding
-  to "EXPLAIN" or "EXPLAIN FORMAT = xxx".
+  number of bytes that should be stripped to skip the digest bytes until
+  the real query.
+
+  Assumed syntax: EXPLAIN [subcommand] [param=value] real_query
 
   @param[in]    digest_storage    Digest storage
 
@@ -51,64 +57,99 @@ namespace im {
 */
 uint calculate_strip_length_for_explain(
     const sql_digest_storage *digest_storage) {
-  uint strip_length = 0;
-
-  if (digest_storage && digest_storage->m_byte_count > EXPLAIN_TOKEN_SIZE) {
-    const unsigned char *src = &digest_storage->m_token_array[0];
-    uint tok = src[0] | (src[1] << 8);
-
-    if (tok == DESCRIBE) {
-      strip_length += 2;
-
-      uint expected_length = EXPLAIN_FORMAT_MINIMAL_LENGTH;
-      if (digest_storage->m_byte_count >=
-          EXPLAIN_TOKEN_SIZE + expected_length + LEAST_TOKEN_SIZE) {
-        /*
-          Make sure that there is enough size for "FORMAT = xxx" and at least
-          one more token.
-         */
-        uint tok_format = src[2] | (src[3] << 8);
-        uint tok_eq = src[4] | (src[5] << 8);
-        uint tok_type = src[6] | (src[7] << 8);
-
-        if (tok_format == FORMAT_SYM && tok_eq == EQ) {
-          /*
-            Note that the format type may also be specified as quoted:
-
-                EXPLAIN FORMAT='TrAdItIoNaL' SELECT 1
-
-            The quoted type is reduced as TOK_GENERIC_VALUE in digest_storage.
-            However, the input token stream is intact and still recognized
-            by the parser.
-           */
-          if (tok_type == JSON_SYM || tok_type == TOK_GENERIC_VALUE)
-            strip_length += expected_length;
-          else if (tok_type == TOK_IDENT) {
-            expected_length += IDENT_LENGTH_SIZE;
-            if (digest_storage->m_byte_count >=
-                EXPLAIN_TOKEN_SIZE + expected_length + LEAST_TOKEN_SIZE) {
-              uint id_len = src[8] | (src[9] << 8);
-              expected_length += id_len;
-              if (digest_storage->m_byte_count >=
-                  EXPLAIN_TOKEN_SIZE + expected_length + LEAST_TOKEN_SIZE) {
-                strip_length += expected_length;
-              } else {
-                // Incomplete identifier payload
-                assert(0);
-              }
-            } else {
-              // Missing identifier length
-              assert(0);
+  const unsigned char *p = digest_storage->m_token_array;
+  const unsigned char *end = p + digest_storage->m_token_array_length;
+
+  // EXPLAIN
+  if (unlikely(!p || (p + SIZE_OF_A_TOKEN) > end)) return 0;
+
+  uint tok = GET_TOKEN(p);
+  if (tok != DESCRIBE) {
+    // OK, non-EXPLAIN
+    return 0;
+  }
+  p += SIZE_OF_A_TOKEN;
+
+  // [subcommand] [param=value] real_query
+  ASSERT_LENGTH(0);
+
+  tok = GET_TOKEN(p);
+  switch (tok) {
+    case FORMAT_SYM: {
+      /*
+        FORMAT = { json | traditional | tree | <quoted> } real_query
+        Note that the format type may also be specified as quoted:
+
+            EXPLAIN FORMAT='TrAdItIoNaL' SELECT 1
+
+        The quoted type is reduced as TOK_GENERIC_VALUE in digest_storage.
+        However, the input token stream is intact and still recognized
+        by the parser.
+       */
+      ASSERT_LENGTH(EXPLAIN_PARAM_MINIMAL_LENGTH);
+      assert(GET_TOKEN(p + SIZE_OF_A_TOKEN) == EQ);
+      switch (GET_TOKEN(p + SIZE_OF_A_TOKEN + SIZE_OF_A_TOKEN)) {
+        case JSON_SYM:  // fallthrough
+        case TOK_GENERIC_VALUE: {
+          p += EXPLAIN_PARAM_MINIMAL_LENGTH;
+          break;
+        }
+        case TOK_IDENT: {
+          p += EXPLAIN_PARAM_MINIMAL_LENGTH;
+          uint len = GET_TOKEN(p);
+          ASSERT_LENGTH(len);
+          p += SIZE_OF_A_TOKEN + len;
+          break;
+        }
+        default: {
+          assert(false);
+          return 0;
+        }
+      }
+      break;
+    }
+    case ANALYZE_SYM:
+      p += SIZE_OF_A_TOKEN;
+      tok = GET_TOKEN(p);
+      switch (tok) {
+        case FORMAT_SYM: {
+          // FORMAT = { tree | <quoted> }
+          ASSERT_LENGTH(EXPLAIN_PARAM_MINIMAL_LENGTH);
+          assert(GET_TOKEN(p + SIZE_OF_A_TOKEN) == EQ);
+          switch (GET_TOKEN(p + SIZE_OF_A_TOKEN + SIZE_OF_A_TOKEN)) {
+            case TOK_GENERIC_VALUE: {
+              p += EXPLAIN_PARAM_MINIMAL_LENGTH;
+              break;
+            }
+            case TOK_IDENT: {
+              p += EXPLAIN_PARAM_MINIMAL_LENGTH;
+              uint len = GET_TOKEN(p);
+              ASSERT_LENGTH(len);
+              p += SIZE_OF_A_TOKEN + len;
+              break;
+            }
+            default: {
+              assert(false);
+              return 0;
             }
-          } else {
-            // Unexpected EXPLAIN format type token
-            assert(0);
           }
-        }  // FORMAT = { json | traditional | tree }
-      }
-    }  // DESCRIBE
+          break;
+        }
+        default:
+          // no parameter
+          assert(GET_TOKEN(p + SIZE_OF_A_TOKEN) != EQ);
+          break;
+      }
+      break;
+    default:
+      // no parameter
+      assert(GET_TOKEN(p + SIZE_OF_A_TOKEN) != EQ);
+      break;
   }
-  return strip_length;
+
+  // The shortest valid statment should be "SELECT 1".
+  assert(p + EXPLAIN_QUERY_MININUM_LENGTH <= end);
+  return (p - digest_storage->m_token_array);
 }
 
 /**