What is hash join in oracle with example?SQL PLSQL
INTRODUCTION: It is the join strategy where the one table data is loaded into the hash table for an efficient lookup. Other table data is scanned to match with the hash table which is suitable for the large datasets. Database optimizer uses the two of the smaller tables to build the hash table into the memory. Its function is used to map join key values to the hash table locations. Larger table is also scanned for each row. It's fast and efficient for quick matching of rows which is based on the join condition. It is an effective when one or both of the tables are large and cannot fit in the memory. It is also effective when the join condition is an equally predicate i.e. table1.column=table2.column. It's cost is limited to the single read pass which is over the two data sets. It is situated in the PGA and the rows are accessed without latching. It will reduce I/O by preventing the necessity of repeatedly latching and reading blocks in the database buffer cache. If the data s...