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Object documentation JOIN_SEARCH_LEVEL Locate the document in its SAP Library structure

The special database parameter JOIN_SEARCH_LEVEL determines the algorithm for the join sequence search. The level specified here determines how many resources and how much time the join sequence search takes.

·         9 (Join sequence search level 9): All possible join sequences are calculated.

·         4 (join sequence level 4): Various join sequences are calculated, depending on the query structure (transformer algorithm).

·         1 (join sequence search level 1): The simplest algorithm is used for the join sequence search (greedy algorithm).

·         0 (classified join sequence search level 0, level 0 is the default setting): The algorithm that is used for the join sequence search depends on the number of tables that were selected in join.
Joins with n number of tables, where n<=JOIN_MAXTAB_LEVEL9: Level 9 of the join sequence search is used.
Joins with n number of tables, where JOIN_MAXTAB_LEVEL9<n<=JOIN_MAXTAB_LEVEL4: Level 4 of the join sequence search is used.
Joins with n number of tables, where JOIN_MAXTAB_LEVEL4<n: Level 1 of the join sequence search is used.

Example

JOIN_MAXTAB_LEVEL4 is set to 16.
JOIN_MAXTAB_LEVEL9 is set to 4.
JOIN_SEARCH_LEVEL is set to 0.
5 tables are used for a join.

Join sequence search level 4 (transformer algorithm) is used for this join because the database parameter JOIN_MAXTAB_LEVEL9<5<=JOIN_MAXTAB_LEVEL4 is most appropriate.

 

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