Tag: 4.3

Valentina for Revolution Supports Now “*b” in the SQL Binding.

Working with Trevore Devore we have found that V4REV do not understand Binary Values if pass them into array of binds.

Problem is that external get array of MCstrings which contain {char*, len}. So external cannot differ strings from binaries.

Solution is like in REV DB. Developer must use prefix “*b” for array items, which contain binary values.
put 1 into binds[1]
put str into binds[2]
put binaryValue into binds[“*b3”]

VREV external now is able to analyze names of array and found binary values.

Internal optimization for views and sub-queries.

In some cases we can avoid copying sub-query result to the temporary table. We can even use sub-query cursor “as is” – so it could be used as a result of the whole query. In other words there  is almost zero overhead against a simple query.

For now such optimization can be applied if a query:

  1. contains only “*” item in the select list clause
  2. has no “where” clause
  3. has no “group by” clause
  4. has no “having” clause
  5. has no “distinct” clause
  6. is not a part of some join operation
  7. has no “order by” clause
  8. has no binding values
  9. sub-query is not a “union/except/intersect” result

Examples:

SELECT * FROM (SELECT * FROM t1 WHERE f1 > 5);

SELECT * FROM (SELECT t1.f1, t2 f1 FROM t1 JOIN t2 ON l1 WHERE t1.f1 > 5 AND t2.f1 <3);