Database query processing

A system for managing a database organized according to a schema, the system comprising:

• a computer-readable medium, the computer readable medium comprising a first file corresponding to a table described by the schema, wherein the first file comprises a first row entry, wherein the first row entry corresponds to a first row of the table, and wherein the first row entry comprises at least one data item;
• and
• at least one processor in communication with the computer-readable medium and programmed to:
• receive a command to modify a first data item in the first row of the table, wherein the command indicates a modified value for the first data item;
• write an indication of the modified value for the first data item to a change location at the first file;
• identify the first row entry from the file;
• and
• write to the first row entry a pointer to the indication of the modified value for the first data item.

A system for managing a database organized according to a schema, the system comprising:

• a computer-readable medium, the computer readable medium comprising a first file corresponding to a table described by the schema, wherein the first file comprises:
• a first change entry comprising a modified value for a first data item, wherein the first change entry is written to a change location of the first file;
• and
• a first row entry, wherein the first row entry corresponds to a first row of the table, and wherein the first row entry comprises at a position corresponding to the first data item, a pointer to the first change entry;
• and
• at least one processor in communication with the computer-readable medium and programmed to:
• receive from a client a query for the first data item;
• determine that the client has not previously received a result for the query;
• load from the first file a plurality of row entries, the plurality of row entries comprising the first row entry;
• modify the loaded first row entry to replace the pointer with the modified value for the first data item;
• and
• return to the client a result of the query, wherein the result of the query comprises the modified value for the first data item.