[jira] [Updated] (IGNITE-7948) SQL: read only necessary fields into the row when possible
[
https://issues.apache.org/jira/browse/IGNITE-7948?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Maxim Muzafarov updated IGNITE-7948:
Fix Version/s: (was: 2.10)
> SQL: read only necessary fields into the row when possible
> --
>
> Key: IGNITE-7948
> URL: https://issues.apache.org/jira/browse/IGNITE-7948
> Project: Ignite
> Issue Type: Task
> Components: sql
>Reporter: Vladimir Ozerov
>Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> When H2 row is read, we always fill it with data eagerly through link
> materialization. Materialization is performed under page "read lock" what
> guarantees row-level consistency. This may lead to excessive memory pressure
> due to memory copying. For example, consider a class with 50 fields and a
> query which reads only 2 of them. 48 other fields will be copied without a
> reason. Lazy initialization is not an option because it will only defer
> memcpy, but not eliminate it.
> Instead we can try using H2. It passes {{TableFilter}} class to some of index
> access methods*. We can analyze this class and create the list of required
> fields. Then we can read these fields under read lock from offheap and put
> them to the row.
> In addition to saved memcpy this could give us more benefits:
> 1) No more need for field cache ({{GridH2KeyValueRowOnheap#valCache}})
> 2) No more need to read {{_VER}} column and possibly {{_KEY}} or {{_VAL}}
> But there are a number of drawbacks as well. E.g. it is impossible to read
> strings from offheap efficiently, so queries with VARCHAR will definitely
> suffer from this change.
> \* {{org.h2.index.Index#find(org.h2.table.TableFilter,
> org.h2.result.SearchRow, org.h2.result.SearchRow)}}
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[jira] [Updated] (IGNITE-7948) SQL: read only necessary fields into the row when possible
[
https://issues.apache.org/jira/browse/IGNITE-7948?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Aleksey Plekhanov updated IGNITE-7948:
--
Fix Version/s: (was: 2.9)
2.10
> SQL: read only necessary fields into the row when possible
> --
>
> Key: IGNITE-7948
> URL: https://issues.apache.org/jira/browse/IGNITE-7948
> Project: Ignite
> Issue Type: Task
> Components: sql
>Reporter: Vladimir Ozerov
>Priority: Major
> Fix For: 2.10
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> When H2 row is read, we always fill it with data eagerly through link
> materialization. Materialization is performed under page "read lock" what
> guarantees row-level consistency. This may lead to excessive memory pressure
> due to memory copying. For example, consider a class with 50 fields and a
> query which reads only 2 of them. 48 other fields will be copied without a
> reason. Lazy initialization is not an option because it will only defer
> memcpy, but not eliminate it.
> Instead we can try using H2. It passes {{TableFilter}} class to some of index
> access methods*. We can analyze this class and create the list of required
> fields. Then we can read these fields under read lock from offheap and put
> them to the row.
> In addition to saved memcpy this could give us more benefits:
> 1) No more need for field cache ({{GridH2KeyValueRowOnheap#valCache}})
> 2) No more need to read {{_VER}} column and possibly {{_KEY}} or {{_VAL}}
> But there are a number of drawbacks as well. E.g. it is impossible to read
> strings from offheap efficiently, so queries with VARCHAR will definitely
> suffer from this change.
> \* {{org.h2.index.Index#find(org.h2.table.TableFilter,
> org.h2.result.SearchRow, org.h2.result.SearchRow)}}
--
This message was sent by Atlassian Jira
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[jira] [Updated] (IGNITE-7948) SQL: read only necessary fields into the row when possible
[
https://issues.apache.org/jira/browse/IGNITE-7948?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Maxim Muzafarov updated IGNITE-7948:
Fix Version/s: (was: 2.8)
2.9
> SQL: read only necessary fields into the row when possible
> --
>
> Key: IGNITE-7948
> URL: https://issues.apache.org/jira/browse/IGNITE-7948
> Project: Ignite
> Issue Type: Task
> Components: sql
>Reporter: Vladimir Ozerov
>Priority: Major
> Fix For: 2.9
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> When H2 row is read, we always fill it with data eagerly through link
> materialization. Materialization is performed under page "read lock" what
> guarantees row-level consistency. This may lead to excessive memory pressure
> due to memory copying. For example, consider a class with 50 fields and a
> query which reads only 2 of them. 48 other fields will be copied without a
> reason. Lazy initialization is not an option because it will only defer
> memcpy, but not eliminate it.
> Instead we can try using H2. It passes {{TableFilter}} class to some of index
> access methods*. We can analyze this class and create the list of required
> fields. Then we can read these fields under read lock from offheap and put
> them to the row.
> In addition to saved memcpy this could give us more benefits:
> 1) No more need for field cache ({{GridH2KeyValueRowOnheap#valCache}})
> 2) No more need to read {{_VER}} column and possibly {{_KEY}} or {{_VAL}}
> But there are a number of drawbacks as well. E.g. it is impossible to read
> strings from offheap efficiently, so queries with VARCHAR will definitely
> suffer from this change.
> \* {{org.h2.index.Index#find(org.h2.table.TableFilter,
> org.h2.result.SearchRow, org.h2.result.SearchRow)}}
--
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