I've listed the issues with the XPLAIN system table docs below, along with some possible solutions if they seem obvious.
rrefsysxplain_statements.dita, STMT_NAME row:
"The name of the associated query or statement. This value is NULL if the user did not assign a name. I'm not sure how the user assigns a name to a statement, perhaps by calling Statement.setCursorName()?"
Do we know the answer to this? Otherwise, I can just remove the question.
rrefsysxplain_resultsets.dita, OP_IDENTIFIER row:
"A code indicating what type of result set these statistics are for. Common result set types include: TABLESCAN, INDEXSCAN, PROJECTION, etc. Should I try to list all the result set types here?"
Are the names easy to find somewhere? (I can't find them, but that means little.) If not, they should be listed; if so, the examples are fine.
rrefsysxplain_resultsets.dita, DEFERRED_ROWS row:
"The column is only non-null for INSERT, UPDATE, and DELETE result sets. For those result sets, this column holds 'Y' if the INSERT/UPDATE/DELETE is being performed using deferred change semantics, and holds 'N' otherwise. I think that deferred change semantics are used when there is self-referencing going on, and we must avoid the "Halloween" problem of processing the rows multiple times."
Can "I think that" be removed? More rephrasing might be helpful.
rrefsysxplain_resultset_timings.dita, TEMP_CONG_CREATE_TIME row:
"For result sets which involve a materialization of a temporary intermediate result set, this value is the time it took to create the materialized result set, in milliseconds. I think this may occur with hash joins where the number of rows in the intermediate result is too large to hold in memory?"
Can "I think" be removed?
rrefsysxplain_scan_props.dita, FETCH_SIZE row:
"I think this is the number of pages fetched at a time when the scan is retrieving pages from disk? I expected this to be 16 when doing a TABLESCAN, and 1 when doing an INDEXSCAN, but I've also seen it be 16 for INDEXSCAN?"
Can this be changed to just "The number of pages fetched at a time when the scan is retrieving pages from disk"?
rrefsysxplain_sort_props.dita, SORT_TYPE row:
"A code indicating the type of sort that was performed. The code values include 'IN' for an internal sort, and 'EX' for an external sort. I think that an internal sort is one which was entirely performed in-memory and did not overflow to any temporary files, while an external sort used one or more external files."
Can "I think that" be removed?