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 <aging...@vmware.com>
Poslano: 10. ožujka 2022. 23:16
Prima: dev@geode.apache.org <dev@geode.apache.org>
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" <mario.k...@est.tech> 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
