Scan Sharing

Queries can reuse data retrieved from storage or operator computations

-> This is different from result caching

Allow multiple queries to attach to a single cursor tha scans a table

• Queries do not have to be exactly the same

• Can also share intermediate results

If a query starts a scan and if there one already doing this, then the DBMS will attach to the second query's cursor

-> The DBMS keeps track of where the second query joined with the first so that it can finish the scan when it reaches the end of the data structure.

Fully supported in IBM DB2 and MSSQL.

Oracle only supports cursor sharing for identical queries