Repository: incubator-hawq
Updated Branches:
  refs/heads/HAWQ-967 0ce866737 -> 9c517d962


HAWQ-975. Added comments.


Project: http://git-wip-us.apache.org/repos/asf/incubator-hawq/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-hawq/commit/9c517d96
Tree: http://git-wip-us.apache.org/repos/asf/incubator-hawq/tree/9c517d96
Diff: http://git-wip-us.apache.org/repos/asf/incubator-hawq/diff/9c517d96

Branch: refs/heads/HAWQ-967
Commit: 9c517d9629a9a3e149b62aa052fba70cc244891c
Parents: 0ce8667
Author: Oleksandr Diachenko <[email protected]>
Authored: Fri Aug 19 17:30:11 2016 -0700
Committer: Oleksandr Diachenko <[email protected]>
Committed: Fri Aug 19 17:30:11 2016 -0700

----------------------------------------------------------------------
 src/backend/access/external/pxffilters.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-hawq/blob/9c517d96/src/backend/access/external/pxffilters.c
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diff --git a/src/backend/access/external/pxffilters.c 
b/src/backend/access/external/pxffilters.c
index bd7588b..405e6d7 100644
--- a/src/backend/access/external/pxffilters.c
+++ b/src/backend/access/external/pxffilters.c
@@ -611,7 +611,13 @@ char *serializePxfFilterQuals(List *quals)
 }
 
 
-
+/*
+ * Returns a list of attributes, extracted from quals.
+ * Supports AND, OR, NOT operations.
+ * Supports =, <, <=, >, >=, IS NULL, IS NOT NULL, BETWEEN, IN operators.
+ * List might contain duplicates.
+ * Caller should release memory once result is not needed.
+ */
 List* extractPxfAttributes(List* quals)
 {
 
@@ -650,8 +656,13 @@ List* extractPxfAttributes(List* quals)
                                break;
                        }
                        default:
-                               /* expression not supported */
-                               elog(ERROR, "extractPxfAttributes: unsupported 
node tag %d, unable to extract column from WHERE clause", tag);
+                               /*
+                                * tag is not supported, it's risk of having:
+                                * 1) false-positive tuples
+                                * 2) unable to join tables
+                                * 3) etc
+                                */
+                               elog(ERROR, "extractPxfAttributes: unsupported 
node tag %d, unable to extract attribute from qualifier", tag);
                                break;
                }
        }

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