I'm building a major product using Lazarus 1.8.4, FPC 3.0.4, IBX 2.3.3 and Firebird RDBMS 3x.  I have a query that runs in the range of 1 to 3 milliseconds without the ORDER BY clause.  But once I add the ORDER BY clause, the query takes > 1.5 seconds.  Be advised that there is an index on the MSGS.PRTY field and an index on the MSG_PSTS.MSTB field.  The PLAN refuses to use either index.  Here is the query SQL:

[code=pascal]

commit;

SELECT

  FIRST 10 SKIP 0

  msg.OBJ_GUID AS "MSG_GUID", msg.PRTY, msg.TTL,

  pst.OBJ_GUID AS "PST_GUID", pst.MSTB_DTS

FROM

  MSGS msg

  JOIN MSG_PSTS pst ON msg.OBJ_GUID = pst.MSG_GUID

  JOIN MSG_USRS meu ON msg.OBJ_GUID = meu.MSG_GUID

  JOIN USRS usr ON msg.USR_GUID = usr.OBJ_GUID

WHERE

  meu.USR_GUID = '12A61B0FAE3046B6AEDEEDF6B4FE0E78'

ORDER BY

  msg.PRTY, pst.MSTB  

[/code]

I almost wish I could create an index on multiple tables somehow.  How can I speed this up?

Here is the PLAN:

[code=pascal]

Select Expression

    -> First N Records

        -> Skip N Records

            -> Sort (record length: 444, key length: 20)

                -> Nested Loop Join (inner)

                    -> Filter

                        -> Table "MSG_USRS" as "MEU" Access By ID

                            -> Bitmap

                                -> Index "FK_MSG_USRS_1" Range Scan (full match)

                    -> Filter

                        -> Table "MSGS" as "MSG" Access By ID

                            -> Bitmap

                                -> Index "PK_MSGS" Unique Scan

                    -> Filter

                        -> Table "USRS" as "USR" Access By ID

                            -> Bitmap

                                -> Index "PK_USRS" Unique Scan

                    -> Filter

                        -> Table "MSG_PSTS" as "PST" Access By ID

                            -> Bitmap

                                -> Index "FK_MSG_PSTS_0" Range Scan (full match)

[/code]

The "Sort" appearing here is the problem.  I need it to go away and get Firebird to use the indexes provided.

Thanks for any help you can provide.