TOAD® Handbook

Repairing Tables with Chained Rows

Sometimes DBAs may need to repair chained rows. Row Fragmentation (RF) or “chaining” occurs when an update increases a row length such that it cannot fit in its current data block and must migrate to a new data block that has sufficient room for the entire row. The only way to correct this problem is to delete those chained rows and re-insert them. This requires creating a temporary table with the same structure as the original to hold those rows between operations. So the actual algorithm is to copy the chained rows to the temporary table, delete them from the original table, and then re-insert them into the original table. TOAD provides the Repair Chained Rows screen, which makes both the detection and correction ...