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Problem: ======== - When an R-tree root page becomes full and requires splitting, InnoDB follows a specific root-raising procedure to maintain tree integrity. The process involves allocating a new page (Page X) to hold the current root's content, preserving the original root page number as the tree's entry point, and migrating all existing records to Page X. The root page is then cleared and reconstructed as an internal node containing a single node pointer with an MBR that encompasses all spatial objects on Page X. Subsequently, InnoDB should split the records on Page X into two spatially optimized groups using the pick_seeds() and pick_next() algorithms, creating a second page (Page Y) for Group B records while retaining Group A records on Page X. After records are redistributed between Page X and Page Y, the recalculated MBR for Page X must remain within or be smaller than the original MBR stored in the root page's node pointer. Bug scenario: ============ - When root page 4 becomes full, it triggers a split operation where the content is copied to page 7 and root page 4 is cleared to become an internal node. - During the first split attempt on page 7, Group 1 overflows and remaining entries are reassigned to Group 2. - A new page 8 is created and the remaining entry record is inserted, but the combined size of the remaining entry record and new record exceeds the page size limit. - This triggers a second split operation on page 7, where Group 2 overflows again and entries are moved back to Group 1. - When the new record is finally inserted into page 7, it causes the MBR (Minimum Bounding Rectangle) for page 7 to expand beyond its original boundaries. - Subsequently, when InnoDB attempts to update the parent page 4 with the new MBR information, it fails to locate the corresponding internal node, leading to spatial index corruption and the reported failure. Problem: ======== - Second split operation should happen on page 8, not on page 7. - split_rtree_node() considers key_size to estimate record sizes during the splitting algorithm, which fails to account for variable-length fields in spatial records. - In rtr_page_split_and_insert(), when reorganization succeeds, InnoDB doesn't attempt the insert the entry Solution: ======== rtr_page_split_and_insert(): InnoDB should do insert the tuple when btr_page_reorganize() is successful. rtr_page_split_and_insert(): Use the overflow page for consecutive split operation. split_rtree_node(): Store the record length for each record in r-tree node. This should give proper estimation while determining the group entries and also helpful in overflow validation |
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