MDEV-21794: Optimizer flag rowid_filter leads to long query

Rowid Filter check is just like Index Condition Pushdown check: before
we check the filter, we must check if we have walked out of the range
we are scanning. (If we did, we should return, and not continue the scan).

Consequences of this:
- Rowid filtering doesn't work for keys that have partially-covered
  blob columns (just like Index Condition Pushdown)
- The rowid filter function has three return values: CHECK_POS (passed)
  CHECK_NEG (filtered out), CHECK_OUT_OF_RANGE.

All of the above is implemented in this patch

1 files changed, 25 insertions, 24 deletions

diff --git a/include/my_compare.h b/include/my_compare.h
index 6568e5f2f27..9ae6c9582fb 100644
--- a/include/my_compare.h
+++ b/include/my_compare.h
@@ -127,31 +127,32 @@ extern HA_KEYSEG *ha_find_null(HA_KEYSEG *keyseg, const uchar *a);
 #endif
 
 /**
-  Return values of index_cond_func_xxx functions.
-
-  0=ICP_NO_MATCH  - index tuple doesn't satisfy the pushed index condition (the
-                    engine should discard the tuple and go to the next one)
-  1=ICP_MATCH     - index tuple satisfies the pushed index condition (the
-                    engine should fetch and return the record)
-  2=ICP_OUT_OF_RANGE - index tuple is out range that we're scanning, e.g. this
-                      if we're scanning "t.key BETWEEN 10 AND 20" and got a
-                      "t.key=21" tuple (the engine should stop scanning and
-                      return HA_ERR_END_OF_FILE right away).
-  3=ICP_ABORTED_BY_USER - engine must stop scanning and should return 
-                         HA_ERR_ABORTED_BY_USER right away
- -1= ICP_ERROR    - Reserved for internal errors in engines. Should not be
-                    returned by index_cond_func_xxx
+  Return values for pushed index condition or rowid filter check functions.
+
+  0=CHECK_NEG  - The filter is not satisfied. The engine should discard this
+                 index tuple and continue the scan.
+  1=CHECK_POS  - The filter is statisfied. Current index tuple should be
+                 returned to the SQL layer.
+  2=CHECK_OUT_OF_RANGE - the index tuple is outside of the range that we're
+                 scanning. (Example: if we're scanning "t.key BETWEEN 10 AND
+                 20" and got a "t.key=21" tuple) Tthe engine should stop
+                 scanning and return HA_ERR_END_OF_FILE right away).
+  3=CHECK_ABORTED_BY_USER - the engine must stop scanning and should return
+                            HA_ERR_ABORTED_BY_USER right away
+ -1=CHECK_ERROR - Reserved for internal errors in engines. Should not be
+                  returned by ICP or rowid filter check functions.
 */
 
-typedef enum icp_result {
-  ICP_ERROR=-1,
-  ICP_NO_MATCH=0,
-  ICP_MATCH=1,
-  ICP_OUT_OF_RANGE=2,
-  ICP_ABORTED_BY_USER=3
-} ICP_RESULT;
-
-typedef ICP_RESULT (*index_cond_func_t)(void *param);
-typedef int (*rowid_filter_func_t)(void *param);
+typedef enum check_result {
+  CHECK_ERROR=-1,
+  CHECK_NEG=0,
+  CHECK_POS=1,
+  CHECK_OUT_OF_RANGE=2,
+  CHECK_ABORTED_BY_USER=3
+} check_result_t;
+
+typedef check_result_t (*index_cond_func_t)(void *param);
+typedef check_result_t (*rowid_filter_func_t)(void *param);
+typedef int (*rowid_filter_is_active_func_t)(void *param);
 
 #endif /* _my_compare_h */