Re: Parallel bitmap heap scan

On Wed, Nov 30, 2016 at 11:08 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
>>
>> patch details
>> 1. hash_support_alloc_free_v1.patch [1].
>> 2. parallel-bitmap-heap-scan-v3.patch

Few assorted comments:

1.
+ else if (needWait)
+ {
+ /* Add ourself to wait queue */
+ ConditionVariablePrepareToSleep(&pbminfo->cv);
+ queuedSelf = true;
+ }

With the committed version of condition variables, you can avoid
calling ConditionVariablePrepareToSleep().  Refer latest parallel
index scan patch [1].

2.
+         <entry><literal>ParallelBitmapScan</></entry>
+         <entry>Waiting for leader to complete the TidBitmap.</entry>
+        </row>
+        <row>

Isn't it better to write it as below:

Waiting for the leader backend to form the TidBitmap.

3.
+ * Update snpashot info in heap scan descriptor.

/snpashot/snapshot

4.
 #include "utils/tqual.h"
-
+#include "miscadmin.h"

 static void bitgetpage(HeapScanDesc scan, TBMIterateResult *tbmres);
-
+static bool pbms_is_leader(ParallelBitmapInfo *pbminfo);

  TBMIterateResult *tbmres;
-
+ ParallelBitmapInfo *pbminfo = node->parallel_bitmap;

 static int tbm_comparator(const void *left, const void *right);
-
+void * tbm_alloc_shared(Size size, void *arg);

It seems line deletes at above places are spurious.  Please check for
similar occurrences at other places in patch.

5.
+ bool is_shared; /* need to build shared tbm if set*/

space is required towards the end of the comment (set */).

6.
+ /*
+ * If we have shared TBM means we are running in parallel mode.
+ * So directly convert dsa array to page and chunk array.
+ */

I think the above comment can be simplified as "For shared TBM,
directly convert dsa array to page and chunk array"

7.
+ dsa_entry = (void*)(((char*)dsa_entry) + sizeof(dsa_pointer));

extra space is missing at multiple places in above line. It should be
written as below:

dsa_entry = (void *)(((char *) dsa_entry) + sizeof(dsa_pointer));

Similar stuff needs to be taken care at other places in the patch as
well.  I think it will be better if you run pgindent on your patch.


-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com