MySQL 9.0.0
Source Code Documentation
|
Fetch the records from a tempoary file. More...
#include <basic_row_iterators.h>
Public Member Functions | |
SortFileIterator (THD *thd, Mem_root_array< TABLE * > tables, IO_CACHE *tempfile, Filesort_info *sort, ha_rows *examined_rows) | |
~SortFileIterator () override | |
bool | Init () override |
Initialize or reinitialize the iterator. More... | |
int | Read () override |
Read a result set record from a temporary file after sorting. More... | |
void | UnlockRow () override |
void | SetNullRowFlag (bool) override |
Mark the current row buffer as containing a NULL row or not, so that if you read from it and the flag is true, you'll get only NULLs no matter what is actually in the buffer (typically some old leftover row). More... | |
Public Member Functions inherited from RowIterator | |
RowIterator (THD *thd) | |
virtual | ~RowIterator ()=default |
RowIterator (const RowIterator &)=delete | |
RowIterator (RowIterator &&)=default | |
virtual const IteratorProfiler * | GetProfiler () const |
Get profiling data for this iterator (for 'EXPLAIN ANALYZE'). More... | |
virtual void | SetOverrideProfiler ([[maybe_unused]] const IteratorProfiler *profiler) |
virtual void | StartPSIBatchMode () |
Start performance schema batch mode, if supported (otherwise ignored). More... | |
virtual void | EndPSIBatchModeIfStarted () |
Ends performance schema batch mode, if started. More... | |
virtual RowIterator * | real_iterator () |
If this iterator is wrapping a different iterator (e.g. More... | |
virtual const RowIterator * | real_iterator () const |
Private Attributes | |
uchar *const | m_rec_buf |
const uint | m_buf_length |
Mem_root_array< TABLE * > | m_tables |
IO_CACHE *const | m_io_cache |
Filesort_info *const | m_sort |
ha_rows *const | m_examined_rows |
Additional Inherited Members | |
Protected Member Functions inherited from RowIterator | |
THD * | thd () const |
Fetch the records from a tempoary file.
There used to be a comment here saying “should obviously not really happen other than in strange configurations”, but especially with packed addons and InnoDB (where fetching rows needs a primary key lookup), it's not necessarily suboptimal compared to e.g. SortBufferIndirectIterator.
SortFileIterator< Packed_addon_fields >::SortFileIterator | ( | THD * | thd, |
Mem_root_array< TABLE * > | tables, | ||
IO_CACHE * | tempfile, | ||
Filesort_info * | sort, | ||
ha_rows * | examined_rows | ||
) |
|
override |
|
inlineoverridevirtual |
Initialize or reinitialize the iterator.
You must always call Init() before trying a Read() (but Init() does not imply Read()).
You can call Init() multiple times; subsequent calls will rewind the iterator (or reposition it, depending on whether the iterator takes in e.g. a Index_lookup) and allow you to read the records anew.
Implements RowIterator.
|
overridevirtual |
Read a result set record from a temporary file after sorting.
The function first reads the next sorted record from the temporary file. into a buffer. If a success it calls a callback function that unpacks the fields values use in the result set from this buffer into their positions in the regular record buffer.
Packed_addon_fields | Are the addon fields packed? This is a compile-time constant, to avoid if (....) tests during execution. |
0 | Record successfully read. |
-1 | There is no record to be read anymore. |
Implements RowIterator.
|
inlineoverridevirtual |
Mark the current row buffer as containing a NULL row or not, so that if you read from it and the flag is true, you'll get only NULLs no matter what is actually in the buffer (typically some old leftover row).
This is used for outer joins, when an iterator hasn't produced any rows and we need to produce a NULL-complemented row. Init() or Read() won't necessarily reset this flag, so if you ever set is to true, make sure to also set it to false when needed.
Note that this can be called without Init() having been called first. For example, NestedLoopIterator can hit EOF immediately on the outer iterator, which means the inner iterator doesn't get an Init() call, but will still forward SetNullRowFlag to both inner and outer iterators.
TODO: We shouldn't need this. See the comments on AggregateIterator for a bit more discussion on abstracting out a row interface.
Implements RowIterator.
|
inlineoverridevirtual |
Implements RowIterator.
|
private |
|
private |
|
private |
|
private |
|
private |
|
private |