Component: QueryResult

Query result represents the outcome of a query This is not just a tuple since aggregation queries produce mutliple result tuples. This module defines routines to marshall / unmarshall query results from tuples and into and out of byte arrays.

Author:

Sam Madden

Required Interfaces

• TupleIntf
• MemAlloc
• ParsedQueryIntf
• Leds

• QueryResultIntf

• command TinyDBError QueryResultIntf.initQueryResult (QueryResultPtr qr)
• short firstQrByte(void)
• command TinyDBError QueryResultIntf.fromTuple (QueryResultPtr qr, ParsedQueryPtr pq, TuplePtr t) Fill out a query result with a single tuple's values Don't just copy a reference to the tuple, since they user may want to generate query results from a specified tuple, and then reuse the tuple for other purposes

• command TinyDBError QueryResultIntf.toTuplePtr (QueryResultPtr qr, ParsedQueryPtr q, TupleHandle t) Return a tuple from a query result.

• command TinyDBError QueryResultIntf.toBytes (QueryResultPtr qr, ParsedQueryPtr pq, CharPtr bytes) Write the query result into the specified byte array.

• command TinyDBError QueryResultIntf.fromBytes (CharPtr bytes, QueryResultPtr qr, ParsedQueryPtr pq, uint8_t startByte) Convert the specified set of bytes into a query result If this result represents an aggregate of multiple fields, This query result must already have been allocated via initQueryResult so that the appropriate storage is available (returns err_OutOfMemory if this is not the case or the byte array is too long to fit in the available storage.) First byte is the offset into bytes to copy from.

• command TinyDBError QueryResultIntf.fromMsgBytes (CharPtr bytes, QueryResultPtr qr, ParsedQueryPtr pq) Decode a query result from result message

• command TinyDBError QueryResultIntf.fromResultTuple (ResultTuple r, QueryResultPtr qr, ParsedQueryPtr pq)
• command short QueryResultIntf.queryIdFromMsg (CharPtr bytes) Return the query id corresponding to a stream of bytes representing a query result (So that callers can determine the value of q to pass into to QUERY_RESULT_FROM_BYTES)

• command uint16_t QueryResultIntf.resultSize (QueryResultPtr qr, ParsedQueryPtr q) Return the size required to store the specified query result in a byte stream, in bytes

• command short QueryResultIntf.numRecords (QueryResultPtr qr, ParsedQueryPtr q)

  Returns:

  the number of records in this result

• command ResultTuple QueryResultIntf.getResultTuple (QueryResultPtr qr, short i, ParsedQueryPtr q) get information about a specified sub tuple

• command TinyDBError QueryResultIntf.addAggResult (QueryResultPtr qr, int16_t groupNo, char *bytes, int16_t size, ParsedQueryPtr q, short exprIdx) Add an agggreate result for the specified query for the specified expression
  • If this query result has already been initialized from a tuple, returns err_AlreadyTupleResult
  • If this query result contains results for a different query id, return err_InvalidQueryId
  • If a alloc is pending, return err_AllocPending

  Parameters:	qr - The query result to add the aggregate data to groupNo - The group number for the aggregate data bytes - The aggregate data size - The size (in bytes) of the aggregate data q - The query this result/data correspond to exprIdx - The expression in q that this is aggregate data for
  Returns:	err_OutOfMemory if there is insufficient space in the result
  	err_AlreadyTupleResult if this query result already has base tuple data in it
  	err_InvalidQueryId qr is not a result for query q
  	err_NoError if there was no error

• event result_t MemAlloc.allocComplete (HandlePtr handle, result_t success)
• event result_t MemAlloc.reallocComplete (Handle handle, result_t success)
• event result_t MemAlloc.compactComplete (void)

QueryResultIntf.toTuplePtr

QueryResultIntf.toBytes