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https://issues.apache.org/jira/browse/IGNITE-17536?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kirill Tkalenko reopened IGNITE-17536:
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> Implement BinaryTuple inlining in a hash index B+Tree
> -----------------------------------------------------
>
> Key: IGNITE-17536
> URL: https://issues.apache.org/jira/browse/IGNITE-17536
> Project: Ignite
> Issue Type: Task
> Reporter: Kirill Tkalenko
> Assignee: Kirill Tkalenko
> Priority: Major
> Labels: ignite-3
> Fix For: 3.0.0-alpha6
>
>
> In a simple implementation, instead of a *BinaryTuple*, we store its link
> from the *FreeList* in the key, this is not optimal and we need to inline the
> *BinaryTuple* in the key, for starters, you can see how to do this in 2.0.
> What should be done:
> * Calculate approximate inline size:
> ** It is set by the user through the configuration or calculated
> automatically, but should not be more than 2 KB (similar to
> *PageIO#MAX_PAYLOAD_SIZE* from 2.0);
> ** For automatic calculation, the *BinaryTuple* format must be taken into
> account: header + null map + offset table;
> *** To cover most cases, we will consider the size class to be 2 bytes
> ([BinaryTupleFormat-Header|https://cwiki.apache.org/confluence/display/IGNITE/IEP-92%3A+Binary+Tuple+Format#IEP92:BinaryTupleFormat-Header]);
> *** For columns of variable length (for example, a string), we will assume
> that 10 bytes should be enough;
> * Write *BinaryTuple* as is up to inline size;
> ** If the user *BinaryTuple* is larger than the inline size, then without its
> transformations (as it is) we will write it according to the inline size (cut
> it off);
> ** If the user *BinaryTuple* is less than or equal to the inline size, then
> we will write it as is without writing it to the FreeList;
> *** At the same time, we need to make a note somewhere that the *BinaryTuple*
> is written in full, this will help us when comparing *BinaryTuple*'s inside
> the B+tree;
> * Comparing *BinaryTuple*'s at B+tree nodes:
> ** If the *BinaryTuple* in the tree node is completely written, then compare
> them without loading the *BinaryTuple* by link (since we will not write it to
> the *FreeList*);
> ** Otherwise, compare *BinaryTuple*'s with loading it by link (we need to do
> it optimally right away).
> The configuration will most likely be done later, since the user experience
> for this is not yet clear.
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