Disclosed aspects relate to query hint learning in a database management system. A hint in a first query is detected by the database management system. The first query has a first signature. A second query is received by the database management system. The second query has a second signature. A determination is made by the database management system that the second signature correlates with the first signature. A query plan is established by the database management system. The query plan is based on the second query and uses the hint in the first query. In response to receiving the second query, the database management system processes the query plan.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A system for query hint learning in a database management system, the system comprising: a memory having a set of computer readable computer instructions, and a processor for executing the set of computer readable instructions, the set of computer readable instructions including: detecting, by the database management system, a hint in a first query, wherein the first query has a first signature; receiving, by the database management system, a second query having a second signature; determining, by the database management system, that the second signature correlates with the first signature; establishing, by the database management system, a query plan which is based on the second query and uses the hint in the first query; and processing, by the database management system in response to receiving the second query, the query plan. 2. The system of claim 1, wherein the first and second signatures are based on a group consisting of at least one of: a parsed Structured Query Language (SQL) statement, an SQL tokenization, a token tree comparison, a table analysis, or a column bitmap. 3. The system of claim 1, wherein processing the query plan includes: providing, using the query plan, a valid results-set for the second query. 4. The system of claim 1, wherein establishing the query plan which is based on the second query and uses the hint in the first query includes: creating a third query which is based on the second query and uses the hint in the first query. 5. The system of claim 4, further comprising: capturing, by processing the second query, a set of second query metadata; capturing, by processing the third query, a set of third query metadata; determining, by comparing the set of second query metadata with the set of third query metadata, that processing the third query has a benefit value with respect to processing the second query; and providing the benefit value. 6. The system of claim 1, wherein the second signature matches the first signature, and further comprising: monitoring, by the database management system in response to detecting the hint in the first query, an incoming query to determine whether an incoming signature of the incoming query matches the first signature, wherein the incoming query includes the second query. 7. The system of claim 1, further comprising: detecting, by the database management system, a second hint in a fourth query, wherein the fourth query has a fourth signature; determining, by the database management system, that the second signature correlates with the fourth signature; and determining, by evaluating a set of hint data which indicates relevancy of both the hint in the first query and the second hint in the fourth query, to use the hint in the first query. 8. The system of claim 7, wherein relevancy is related to a set of index costs. 9. The system of claim 8, wherein the set of index costs includes a second index cost for the second query and a query plan index cost for the query plan, and wherein the query plan index cost exceeds the second index cost. 10. The system of claim 1, further comprising: calculating a first proportion of a table of the database management system which is selected when processing the first query; calculating a second proportion of the table of the database management system which is selected when processing the second query; and determining the second proportion is within a mathematical threshold of the first proportion. 11. The system of claim 1, further comprising: computing a first index for the first query; computing a second index for the second query; and determining an index similarity relationship with respect to the second index and the first index. 12. The system of claim 1, further comprising: computing a set of first index fields of a first index for the first query; computing a set of second index fields of a second index for the second query; and determining a field similarity relationship between the set of second index fields and the set of first index fields. 13. The system of claim 1, further comprising: calculating a first proportion of a table of the database management system which is selected when processing the first query based on a first field; calculating a second proportion of the table of the database management system which is selected when processing the second query based on a second field, wherein the second field differs from the first field; and determining the second proportion is within a mathematical threshold of the first proportion. 14. The system of claim 1, wherein establishing the query plan which is based on the second query and uses the hint in the first query includes using a machine-learning technique to learn from the first query. 15. The system of claim 1, wherein the hint includes a selection from a group consisting of at least one of: a table scan, an index choice, an index implementation, a join order, a join implementation, a statistic, a grouping implementation, an ordering implementation, a database code level, an optimization goal, a fair memory share, live data, a processing intensive goal, a parameter marker implementation, or a materialization goal. 16. The system of claim 1, further comprising: detecting, by the database management system, a second hint in a fourth query, wherein the fourth query has a fourth signature; determining, by the database management system, that the second signature correlates with the fourth signature; determining, by evaluating a set of hint data which indicates relevancy of both the hint in the first query and the second hint in the fourth query, to use the hint in the first query; calculating a first proportion of a table of the database management system which is selected when processing the first query; calculating a second proportion of the table of the database management system which is selected when processing the second query; determining the second proportion is within a mathematical threshold of the first proportion; computing a first index for the first query; computing a second index for the second query; and determining an index similarity relationship with respect to the second index and the first index. 17. The system of claim 16, wherein: the first and second signatures are based on a first group consisting of at least one of: a parsed Structured Query Language (SQL) statement, an SQL tokenization, a token tree comparison, a table analysis, or a column bitmap; the hint includes a selection from a second group consisting of at least one of: a table scan, an index choice, an index implementation, a join order, a join implementation, a statistic, a grouping implementation, an ordering implementation, a database code level, an optimization goal, a fair memory share, live data, a processing intensive goal, a parameter marker implementation, or a materialization goal; relevancy is related to a set of index costs; the set of index costs includes a second index cost for the second query and a query plan index cost for the query plan; and the query plan index cost exceeds the second index cost. 18. A computer program product for query hint learning in a database management system, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, wherein the computer readable storage medium is not a transitory signal per se, the program instructions executable by a processor to cause the processor to perform a method comprising: detecting, by the database management system, a hint in a first query, wherein the first query has a first signature; receiving, by the database management system, a second query having a second signature; determining, by the database management system, that the second signature correlates with the first signature; establishing, by the database management system, a query plan which is based on the second query and uses the hint in the first query; and processing, by the database management system in response to receiving the second query, the query plan. 19. The computer program product of claim 18, wherein the program instructions are stored in a computer readable storage medium in a data processing system, and wherein the program instructions were downloaded over a network from a remote data processing system. 20. The computer program product of claim 18, wherein the program instructions are stored in a computer readable storage medium in a server data processing system, and wherein the program instructions are downloaded over a network to a remote data processing system for use in a computer readable storage medium with the remote data processing system.