[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487624#comment-14487624 ] Anuj commented on CASSANDRA-8938: - Agree !! > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
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https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487564#comment-14487564
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Tyler Hobbs commented on CASSANDRA-8938:
[~eanujwa] so, there are two separate issues here: the read count and latency
metrics (what you see in cfstats), and the hotness measurements for sstables.
We don't have to update them the same way.
Regarding metrics, I would be okay with having separate range scan count and
latency metrics. We need to decide exactly those metrics behave, though (e.g.
increment the read count for each full scan, or each partition scanned, or each
row scanned?).
For the hotness measurements, I do _not_ think we should increment the read
count for each row (or even partition) in a scan. After the removal of
{{cold_reads_to_omit}} in CASSANDRA-8860, the hotness measurements do two
things: prioritize compaction of certain sstables when there are multiple
sstable sets that can be compacted, and determine the amount of space to
allocate for the index summary for an sstable. Since the index summary is far
more important for partition reads than scans, I think we can agree that scans
shouldn't have a big impact on this. For prioritizing compaction, the absolute
read numbers don't matter, only how large they are relative to each other. So,
incrementing the count by one for each scan should be sufficient to handle a
scan-only workload. If the workload is mixed, I think it's okay if partition
reads have a greater influence on compaction prioritization than range scans do.
> Full Row Scan does not count towards Reads
> --
>
> Key: CASSANDRA-8938
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8938
> Project: Cassandra
> Issue Type: Bug
> Components: API, Core, Tools
> Environment: Unix, Cassandra 2.0.3
>Reporter: Amit Singh Chowdhery
>Assignee: Marcus Eriksson
>Priority: Minor
> Labels: none
>
> When a CQL SELECT statement is executed with WHERE clause, Read Count is
> incremented in cfstats of the column family. But, when a full row scan is
> done using SELECT statement without WHERE clause, Read Count is not
> incremented.
> Similarly, when using Size Tiered Compaction, if we do a full row scan using
> Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra
> still considers all sstables as cold and does not trigger compaction for
> them. If we fire MultigetSliceQuery, Read Count is incremented and sstables
> becomes hot, triggering compaction of these sstables.
> Expected Behavior:
> 1. Read Count must be incremented by number of rows read during a full row
> scan done using CQL SELECT statement or Hector RangeslicesQuery.
> 2. Size Tiered compaction must consider all sstables as Hot after a full row
> scan.
--
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[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487439#comment-14487439 ] Anuj commented on CASSANDRA-8938: - In our case we do some reporting using full table scans in off hours when resources are free. We dont have an Analytics system like Spark. If sstables are not compacted it affects reporting performance badly. So I think Cassandra should be unbiased. If a data is read actively we will gain performance in bothh workloads. Compaction will have cost and will impact transactional resources temporarily but further Analytics hits would be much faster and those hits will put less load on cassandra resources if tables are compacted. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487423#comment-14487423 ] Anuj commented on CASSANDRA-8938: - I think counting it as one read would make the ready latency in cfstats misleading as range scan may return nunerous rows and is generally slower. What about having a separate Range scan count and latency. Range scan count can be equal to rows read in scan. I think if a range scan reads several rows from a sstable it should impact hotness propotionately. Cassandra should not worry about the type of workload as data is being read and compaction will be useful whether its analytics or oltp. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14389253#comment-14389253 ] Jonathan Ellis commented on CASSANDRA-8938: --- Sounds reasonable. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=1431#comment-1431 ] Tyler Hobbs commented on CASSANDRA-8938: Historically we have excluded range scans from counting towards sstable hotness on purpose, but perhaps we should reconsider. A good cluster setup may use multiple DCs to split analytical and transactional workloads. In that scenario, we would ideally measure sstable hotness in the analytical DC by range scans. Even if analytical and transactional workloads are both run on the same nodes, the range scans should account for a comparatively small percentage of reads, so they shouldn't impact the hotness measurements by very much. In other words, I think it would be safe to let a range scan count for one read (and adjust the hotness measurement accordingly). > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14386793#comment-14386793 ] Anuj commented on CASSANDRA-8938: - Even though single partition read and range scan are technically different, from Application point of view they are just reads. I feel that scans should also make sstables "HOT" and make them eligible for STCS. Regarding nodetool cfstats, if Read count and Read Latency are not including scans , Don't you think we should have stats for scan count and latency ? > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14386768#comment-14386768 ] Jonathan Ellis commented on CASSANDRA-8938: --- Yes, we've always considered "read [single partiton]" and "scan" to be separate things. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14386292#comment-14386292 ] Marcus Eriksson commented on CASSANDRA-8938: depends I guess, one could consider a range scan an analytics workload where it shouldn't count towards hotness of sstables (ie, you have regular real queries and then periodically you do range queries and you don't want them to affect the real queries) [~thobbs] do you remember if this was on purpose? > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14376597#comment-14376597 ] Philip Thompson commented on CASSANDRA-8938: [~krummas], is it correct behavior for STCS to still consider all sstables as cold after full scans? > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Assignee: Marcus Eriksson >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358326#comment-14358326 ] Phil Yang commented on CASSANDRA-8938: -- The "readLatency" is a counter both counting "read count" and "read latency" for the query with WHERE clause. I think the reason that nodetool only show the count of readLatency rather than readLatency+rangeLatency is that usually it is not a good idea to select the whole table(because it will read all sstables in all nodes) so it is not commonly used and usually be zero. Anyone other think the read count and read latency should add the counter of range read? Why do you think all sstables must be available for next compaction after a range read? It has few help for range read and compaction will increase the load of all nodes. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358327#comment-14358327 ] Phil Yang commented on CASSANDRA-8938: -- The "readLatency" is a counter both counting "read count" and "read latency" for the query with WHERE clause. I think the reason that nodetool only show the count of readLatency rather than readLatency+rangeLatency is that usually it is not a good idea to select the whole table(because it will read all sstables in all nodes) so it is not commonly used and usually be zero. Anyone other think the read count and read latency should add the counter of range read? Why do you think all sstables must be available for next compaction after a range read? It has few help for range read and compaction will increase the load of all nodes. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358306#comment-14358306 ] Anuj commented on CASSANDRA-8938: - Yes. We mean full row scan (select query without "WHERE" clause). Even if full row scan reads all sstables,it should be considered as Reads and all sstables must be marked "hot" and available for next compaction. There is only one "Read Count" when you do cfstats. We are not talking about latency. We think that after a row scan , read count must be incremented and STCS should pick these sstables for compaction as data has been read from them. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358257#comment-14358257 ] Phil Yang commented on CASSANDRA-8938: -- I'm not an expert. Do you mean "full row scan" is selecting all rows in a table? The full table scan seems need to read all sstables, so compaction that reduces the number of sstables will not reduce the disk IO while scanning the whole row. I think it is the reason that sstables will not be marked as hot after the full row scan. For your first question, it seems that there are two read counter, one is "readLatency" the other is "rangeLatency", and nodetool only returns the count of the first one so your scan query does not affect it. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Commented] (CASSANDRA-8938) Full Row Scan does not count towards Reads
[ https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358038#comment-14358038 ] Amit Singh Chowdhery commented on CASSANDRA-8938: - Could somebody pls have a look in this issue...Thanks in advance. > Full Row Scan does not count towards Reads > -- > > Key: CASSANDRA-8938 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8938 > Project: Cassandra > Issue Type: Bug > Components: API, Core, Tools > Environment: Unix, Cassandra 2.0.3 >Reporter: Amit Singh Chowdhery >Priority: Minor > Labels: none > > When a CQL SELECT statement is executed with WHERE clause, Read Count is > incremented in cfstats of the column family. But, when a full row scan is > done using SELECT statement without WHERE clause, Read Count is not > incremented. > Similarly, when using Size Tiered Compaction, if we do a full row scan using > Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra > still considers all sstables as cold and does not trigger compaction for > them. If we fire MultigetSliceQuery, Read Count is incremented and sstables > becomes hot, triggering compaction of these sstables. > Expected Behavior: > 1. Read Count must be incremented by number of rows read during a full row > scan done using CQL SELECT statement or Hector RangeslicesQuery. > 2. Size Tiered compaction must consider all sstables as Hot after a full row > scan. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
