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From Anilkumar Gingade <aging...@pivotal.io>
Subject Re: [DISCUSS] Addition of isValid API to Index interface
Date Fri, 08 Sep 2017 22:04:17 GMT
Indexes are critical for querying; most of the databases doesn't allow
insert/update if there is any failure with index maintenance...

As Geode OQL supports two ways (sync and async) to maintain the indexes, we
need be careful about the error handling in both cases...

My take is:
1. For synchronous index maintenance:
If there is any failure in updating any index (security/auth or logical
error) on the region; throw an exception and rollback the cache update/op
(index management id done under region.entry lock - we should be able to
revert the op). If index or cache is left in bad state, then its a bug that
needs to be addressed.

Most of the time, If there is any logical error in index, it will be
detected as soon as index is created (on existing data) or when first
update is done to the cache.

2. For Asynchronous index maintenance:
As this is async (assuming) user has good understanding of the risk
involved with async, any error with index maintenance, the index should be
invalidated...

 About the security/auth, the user permission with region read/write needs
to be applied for index updates, there should not be different permission
on index.

-Anil.



On Fri, Sep 8, 2017 at 2:01 PM, Nabarun Nag <nnag@pivotal.io> wrote:

> Hi Mike,
>
> Please do find our answers below:
> *Question:* What if there were multiple indices that were in flight and
> only the third
> one errors out, will they all be marked invalid?
>
> *Answer:* Only the third will be marked invalid and only the third one will
> not be used for query execution.
>
> *Question/Statement:* If anything goes wrong with the put it should
> probably still throw back to
> the caller. Silent invalidation of the index is probably not desirable.
>
> *Answer: *
> In our current design this the flow of execution of a put operation:
> entry put into region -> update index -> other wan related executions /
> callbacks etc.
>
> If an exception happens while updating the index, the cache gets into a bad
> state, and we may end up getting different results depending on the index
> we are using. As the failure happens half way in a put operation, the
> regions / cache are now in a bad state.
> --------------------------
> We are thinking that if index is created  over a method invocation in an
> empty region and then we do puts, but method invocation is not allowed as
> per security policies. The puts will now be successful but the index will
> be rendered invalid. Previously the puts will fail with exception and put
> the entire cache in a bad state.
>
>
>
> Regards
> Nabarun
>
>
>
>
>
> On Fri, Sep 8, 2017 at 10:43 AM Michael Stolz <mstolz@pivotal.io> wrote:
>
> > Just to help me understand, the index is corrupted in a way beyond just
> the
> > field that errors out?
> > What if there were multiple indices that were in flight and only the
> third
> > one errors out, will they all be marked invalid?
> > If anything goes wrong with the put it should probably still throw back
> to
> > the caller. Silent invalidation of the index is probably not desirable.
> >
> > --
> > Mike Stolz
> > Principal Engineer, GemFire Product Manager
> > Mobile: +1-631-835-4771 <(631)%20835-4771>
> >
> > On Fri, Sep 8, 2017 at 12:34 PM, Dan Smith <dsmith@pivotal.io> wrote:
> >
> > > +1
> > >
> > > -Dan
> > >
> > > On Thu, Sep 7, 2017 at 9:14 PM, Nabarun Nag <nnag@apache.org> wrote:
> > >
> > > > *Proposal:*
> > > > * Index interface will include an API - isValid() which will return
> > true
> > > if
> > > > the index is still valid / uncorrupted, else will return false if it
> > > > corrupted / invalid.
> > > > * gfsh command "list index" will have one more column "Is Valid"
> which
> > > will
> > > > state the status as "true" or "false".
> > > > * Invalid indexes will not be used during query executions.
> > > > * In case the index is found to be invalid, the user will be able to
> > > > remove/destroy the index.
> > > > * When a put operation corrupts an index, it will be logged.
> > > >
> > > > *Reasoning:*
> > > > * Currently if a put operation raises an exception while updating the
> > > > index, the put operation fails with an exception to the putter.
> > > > * For example, if an index is created on an object method, and that
> > > method
> > > > causes an exception while updating the index as a part of a put
> > > operation,
> > > > then the put operation fails for that particular entry and the index
> is
> > > > left in a bad state.
> > > > * This may occur also due to lack of permission to update index but
> > have
> > > > permission to do puts.
> > > > * We are proposing that in the above mentioned scenarios, the put
> > > succeeds
> > > > in putting the entry in the region but the index which it was trying
> to
> > > > update will be marked invalid and will not be used for query
> > executions.
> > > > * This can be justified because the corrupted index will not
> correctly
> > > > represent the region entries.
> > > >
> > > > *Status Quo:*
> > > > * Index creation will still fail if we are trying to create an index
> > > over a
> > > > region containing an entry/entries  which will cause an exception
> while
> > > > loading the entry into the index.
> > > >
> > > > Regards
> > > > Nabarun Nag
> > > >
> > >
> >
>

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