Re: GSoC 2017: weekly progress reports (week 6)

On Sat, Sep 30, 2017 at 6:12 PM, Shubham Barai <shubhambaraiss(at)gmail(dot)com>
wrote:

> I have made changes according to your suggestions. Please have a look at
> the updated patch.
> I am also considering your suggestions for my other patches also. But, I
> will need some time to
> make changes as I am currently busy doing my master's.
>

I don't understand why sometimes you call PredicateLockPage() only when
fast update is off. For example:

@@ -94,6 +101,9 @@ scanPostingTree(Relation index, GinScanEntry scanEntry,
> break; /* no more pages */
>
> buffer = ginStepRight(buffer, index, GIN_SHARE);
> +
> + if (!GinGetUseFastUpdate(index))
> + PredicateLockPage(index, BufferGetBlockNumber(buffer), snapshot);
> }
>
> UnlockReleaseBuffer(buffer);

But sometimes you call PredicateLockPage() unconditionally.

@@ -131,6 +141,8 @@ collectMatchBitmap(GinBtreeData *btree, GinBtreeStack
> *stack,
> attnum = scanEntry->attnum;
> attr = btree->ginstate->origTupdesc->attrs[attnum - 1];
>
> + PredicateLockPage(btree->index, stack->buffer, snapshot);
> +
> for (;;)
> {
> Page page;

As I understand, all page-level predicate locking should happen only when
fast update is off.

Also, despite general idea is described in README-SSI, in-code comments
would be useful.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company