As an fyi, in the past we disabled applying limits at the index level for range
indexes.
I’m surprised in this case that we would add all the entries to the
intermediate results instead of applying the filter first and checking the
condition before adding to the intermediate results..
I would have thought it would have to apply the condition as seen in
CompactRangeIndex.addToResultsFromEntries :
if (ok && runtimeItr != null && iterOps != null) {
ok = QueryUtils.applyCondition(iterOps, context);
}
I haven’t walked this query through the code, perhaps it’s hitting a different
index type (I’d think a map index but that probably is backed by
CompactRangeIndexes for each key…)
From: Jason Huynh <[email protected]>
Date: Friday, March 11, 2022 at 12:47 PM
To: [email protected] <[email protected]>
Subject: Re: Question about INDEX_THRESHOLD_SIZE
I think https://github.com/apache/geode/pull/7010 may have changed what that
property represented. I believe it was some arbitrary threshold to abort using
index look ups (if the intermediate results were small, it was deemed faster to
just iterate through and not do a lookup – at least from my interpretation of
the code)
It looks like with the change, it now munges it with limit.. so now limit is
applied to that value.. gfsh happens to always pass in a limit too, so there is
possibly additional confusion
From the diff there is also one spot where a limit != -1 had not been added..
In CompactRangeIndex line 489:
if (limit < indexThresholdSize) {
limit = indexThresholdSize;
}
This might be affecting the usage of limit at the index level?
From: Anilkumar Gingade <[email protected]>
Date: Friday, March 11, 2022 at 12:11 PM
To: [email protected] <[email protected]>
Subject: Re: Question about INDEX_THRESHOLD_SIZE
Mario,
There is similar test/example added by you in QueryWithRangeIndexDUnitTest.
testQueryWithWildcardAndIndexOnAttributeFromHashMap()
When I run that test (on develop); I see the results as expected:
*************
Command result for <query --query="<trace> select e.key, e.value from
/exampleRegion.entrySet e where e.value.positions['SUN'] like 'somethin%'">:
Result : true
Limit : 100
Rows : 1
Query Trace : Query Executed in 85.1964 ms; indexesUsed(1):IdIndex(Results:
10000)
************
Are you running your test with any additional change like as you are saying :
>> I was working on allowing INDEX_THRESHOLD_SIZE System property to override
>> CompiledValue.RESULT_LIMIT.
If so , you need to look at the change and see why its impacting that way.
If not, please let me know what change can be made in that test to reproduce
the issue you are seeing; that will help to debug/analyze the issue.
-Anil.
On 3/11/22, 12:18 AM, "Mario Kevo" <[email protected]> wrote:
Hi,
It works without an index but it doesn't work with an index.
When I revert changes, it takes INDEX_THRESHOLD_SIZE default value(100).
And if the entry that matches the condition is not in that resultset it will
not be printed.
Without index:
gfsh>query --query="<trace>SELECT e.key, e.value from
/example-region.entrySet e where e.value.positions['SUN'] like 'someth%'"
Result : true
Limit : 100
Rows : 1
Query Trace : Query Executed in 11.502283 ms; indexesUsed(0)
key | value
--- |
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
300 |
{"ID":300,"indexKey":0,"pkid":"300","shortID":null,"position1":{"mktValue":1945.0,"secId":"ORCL","secIdIndexed":"ORCL","secType":null,"sharesOutstanding":1944000.0,"underlyer":null,"pid":1944,"portfolioId":300,..
With index:
gfsh>query --query="<trace>SELECT e.key, e.value from
/example-region.entrySet e where e.value.positions['SUN'] like 'someth%'"
Result : true
Limit : 100
Rows : 0
Query Trace : Query Executed in 8.784831 ms; indexesUsed(1):index1(Results:
100)
BR,
Mario
________________________________
Šalje: Anilkumar Gingade <[email protected]>
Poslano: 10. ožujka 2022. 23:16
Prima: [email protected] <[email protected]>
Predmet: Re: Question about INDEX_THRESHOLD_SIZE
Mario,
There are few changes happened around this area as part of GEODE-9632 fix;
can you please revert that change and see if the query works both with and
without index.
Looking at the code; it seems to restrict the number index look up that
needs to be performed; certain latency/throughput sensitive queries that or not
expecting exact result may use this (my guess) but by default it should not be
resulting in unexpected results.
-Anil.
On 3/10/22, 6:50 AM, "Mario Kevo" <[email protected]> wrote:
Hi geode-dev,
Some time ago I was working on allowing INDEX_THRESHOLD_SIZE System
property to override CompiledValue.RESULT_LIMIT.
After this change, adding this attribute will take into a count if you
set it.
But I need some clarification of this INDEX_THRESHOLD_SIZE attribute.
Why is this set by default to 100?
The main problem with this attribute is that if you want to get the
correct result, you need to know how many entries will be in the region while
starting servers and set it on that value or higher. Sometimes it is too hard
to know how many entries will be in the region, so maybe better will be to set
it by default to some higher number, something like Integer.MAX_VALUE.
Where this attribute is used?
It is used to get index results while doing queries.
What is the problem?
If we have INDEX_THRESHOLD_SIZE set to 500, and we have 1k entries it
can happen that while doing a query it will get only 500 entries and where
clause cannot be fulfilled and we got no results.
Let's see it by an example!
We have only one entry that matches the condition from the query,
INDEX_THRESHOLD_SIZE set to 500, and 1k entries in the region.
If we run the query without an index we got the result.
gfsh>query --query="<trace>SELECT e.key, e.value from
/example-region.entrySet e where e.value.positions['SUN'] like 'someth%'"
Result : true
Limit : 100
Rows : 1
Query Trace : Query Executed in 10.750238 ms; indexesUsed(0)
key | value
--- |
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
700 |
{"ID":700,"indexKey":0,"pkid":"700","shortID":null,"position1":{"mktValue":1945.0,"secId":"ORCL","secIdIndexed":"ORCL","secType":null,"sharesOutstanding":1944000.0,"underlyer":null,"pid":1944,"portfolioId":700,..
If we create an index and then run again this query there is no result.
gfsh>query --query="<trace>SELECT e.key, e.value from
/example-region.entrySet e where e.value.positions['SUN'] like 'someth%'"
Result : true
Limit : 100
Rows : 0
Query Trace : Query Executed in 22.079016 ms;
indexesUsed(1):index1(Results: 500)
This happened because we have no luck getting that entry that matches
the condition in the intermediate results for the index.
So the questions are:
What if more entries enter the region that will make the index return
more entries than this threshold sets? Then we're again in jeopardy that the
query condition will not match.
Why is this attribute set by default to 100?
Can we change it to the Integer.MAX_VALUE by default to be sure that we
have the correct result? What are the consequences?
BR,
Mario
