Abstract: Techniques are described herein that are capable of using a semantic tree of a compiler to execute a semantic code query against source code. An object model representing the source code is generated. The object model includes the semantic tree, which is based at least in part on a grammar defined at least in part by the object model and an application programming interface (API) exposed by the compiler. The semantic code query, which is written in a code query language associated with the compiler, is received as an input to the compiler. The semantic code query includes search criteria. A portion of the source code that satisfies the search criteria is determined using the API. A result of the semantic code query is provided. The result identifies the portion of the source code that satisfies the search criteria.

Abstract: A database table is provided. The database table includes several column tuples. A column is selected in the database table. The column tuples of the selected column are partitioned into several bins. Each bin includes a range of tuples and associated metadata. The associated metadata includes at least one of: a minimum tuple value for the tuples in the bin, a maximum tuple value for the tuples in the bin, a minimum tuple identifier for the bin and a maximum tuple identifier for the bin. The bins are sorted based on the tuple values to provide an approximate index for the database.

Abstract: A method for estimating contents of a cache determines table descriptors referenced by a query, and scans each page header stored in the cache for the table descriptor. If the table descriptor matches any of the referenced table descriptors, a page count value corresponding to the matching referenced table descriptor is increased. Alternatively, a housekeeper thread periodically performs the scan and stores the page count values in a central lookup table accessible by threads during a query run. Alternatively, each thread independently maintains a hash table with page count entries corresponding to table descriptors for each table in the database system. A thread increases or decreases the page count value when copying or removing pages from the cache. A page count value for each referenced table descriptor is determined from a sum of the values in the hash tables. A master thread performs bookkeeping and prevents hash table overflows.

Abstract: A database table is provided. The database table includes several column tuples. A column is selected in the database table. The column tuples of the selected column are partitioned into several bins. Each bin includes a range of tuples and associated metadata. The associated metadata includes at least one of: a minimum tuple value for the tuples in the bin, a maximum tuple value for the tuples in the bin, a minimum tuple identifier for the bin and a maximum tuple identifier for the bin. The bins are sorted based on the tuple values to provide an approximate index for the database.

Abstract: A method for estimating contents of a cache determines table descriptors referenced by a query, and scans each page header stored in the cache for the table descriptor. If the table descriptor matches any of the referenced table descriptors, a page count value corresponding to the matching referenced table descriptor is increased. Alternatively, a housekeeper thread periodically performs the scan and stores the page count values in a central lookup table accessible by threads during a query run. Alternatively, each thread independently maintains a hash table with page count entries corresponding to table descriptors for each table in the database system. A thread increases or decreases the page count value when copying or removing pages from the cache. A page count value for each referenced table descriptor is determined from a sum of the values in the hash tables. A master thread performs bookkeeping and prevents hash table overflows.