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https://issues.apache.org/jira/browse/IGNITE-23120?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17986333#comment-17986333
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Philipp Shergalis edited comment on IGNITE-23120 at 6/26/25 11:35 AM:
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[~timonin.maksim] Hi! There is a SO discussion with explanation:
[https://stackoverflow.com/questions/78932092/is-there-a-correlation-between-index-inline-size-and-index-column-datastring-ty]
It actually leads to node failing, ticket description is misleading
Constant (for 1KB page) limit is used because page size is not available on
client nodes, but they also calculate inline size
This constant is too strict for clients with larger page size, but I was told
that inline size shouldn't be very big and it's not a problem
was (Author: JIRAUSER303902):
[~timonin.maksim] Hi! There is a SO discussion with explanation:
[https://stackoverflow.com/questions/78932092/is-there-a-correlation-between-index-inline-size-and-index-column-datastring-ty]
It actually leads to node failing, ticket description is misleading
Constant (for 1KB page) limit is used because page size is not available on
client nodes and it seems impossible to calculate it with actual page size
This constant is too strict for clients with larger page size, but I was told
that inline size shouldn't be very big and it's not a problem
> Improve inline index feature
> ----------------------------
>
> Key: IGNITE-23120
> URL: https://issues.apache.org/jira/browse/IGNITE-23120
> Project: Ignite
> Issue Type: Improvement
> Reporter: Vladimir Pligin
> Assignee: Philipp Shergalis
> Priority: Major
>
> Ignite allows index rows to be inlined directly into the page. However, it
> doesn’t guard properly against too big inline size values. Currently, it uses
> {{PageIO.MAX_PAYLOAD_SIZE}} as the maximum allowed value, but this value can
> still be too large, because it does not take the page size and encryption
> (which adds additional bytes to the page header) into account. This possibly
> leads to a bad situation when only one item can fit in one page which can
> lead to BTree performance degradation.
> The following is expected to be done:
> # When inline size for an index is set, a maximum inline size should be
> computed:
> ## Considering we want to have _at least_ 2 items per page, here’s how the
> page layout with max inline size will look like: {{PS = H + L + I + L + I +
> L}} . Where PS - Page Size, H - page header size, L - size of the child link,
> I - item size.
> ## Using the above equation, we get the max possible item size to be equal
> to: {{I = (PS - H - 3L) / 2}} . However, for inline indexes, every item has
> an additional overhead to the actual inlined value (a.k.a payload), which
> depends on MVCC being present.
> ## Taking this into account, the maximum payload size will be equal: {{P =
> (PS - H - 3L) / 2 - X}} , where P - Payload size, X - overhead per item.
> ## In implementation terms, {{PS}} must be computed using the
> {{PageMemory#realPageSize}} which takes encryption overhead into
> account,{{{}H{}}} is equal to {{{}BPlusIo#ITEMS_OFF{}}}, {{L}} is 8 bytes and
> {{X}} depends on the actual {{AbstractH2ExtrasInnerIO}} implementation and
> varies between 8 and 28 bytes.
> # If the configured inline size exceeds the computed maximum size or
> {{PageIO.MAX_PAYLOAD_SIZE}} then an exception must be thrown with a message
> that notifies the user of the incorrect inline size value. Note that this
> should only happen for _new_ indexes, if a nodes is started on top of an
> existing PDS, no exceptions should be thrown and a warning should be printed
> instead, to preserve backwards compatibility.
> # Fix the “Indexed columns of a row cannot be fully inlined into index”
> warning to recommend at most the maximum allowed inline size.
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