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Re: reusing transactions in LMDB

Tim Uckun wrote:

Sorry for being so dense but...

The document says

The transaction handle is freed. It and its cursors must not be used again
after this call, except with mdb_cursor_renew().

I am still very confused about reusing transactions.

Keep reading.

If I commit or abort a read write transaction I can't reuse the transaction
but I can re use the cursor? In the cursor documentation it says

 Cursors that are only used in read-only transactions may be re-used, to avoid
unnecessary malloc/free overhead.

So this indicates only read only cursors can be reused right?


So can you confirm my understanding? This is what I get from reading the docs.

A transaction can either be read write or read only.

If a transaction is read only you can commit or abort the transaction and then
re-open it again for further use.

No. Once a transaction is committed or aborted it is freed and cannot be reused. Period, end of story. Both the commit() and abort() docs are quite explicit about this.

If a transaction is read write then it can't be used again after you commit or
abort the transaction.

On Tue, Nov 22, 2016 at 3:17 PM, Howard Chu <hyc@symas.com
<mailto:hyc@symas.com>> wrote:

    Tim Uckun wrote:

            No. You can perform multiple write operations in a single transaction.

        But once the commit has been called the next write operation has to be
        a newly
        opened transaction right?  The write transactions can't be re-opened.


  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/