The query optimizer is the component of a database management system that attempts to determine the most efficient way to execute a query.

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want to optimize this query by removing two SELECT and two JOINS

SELECT t3.transaction_pci_details_id, t3.terminal_id, t3.transaction_no, t4.transaction_id, t3.transaction_type, t3.reversal_flag, t3.transmission_date_time, t4.retrivel_ref_no, t3.card_no, ...
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How to count selectivity rows in PostgreSQL 8.2

I have problem with two queries on PostgreSQL v8.2. It seem like the optimizer chooses a wrong index: db=# explain select count(*), messagetype, alias from event where templateinfoid = 10 and ...
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Oracle 11g bug ? not returning the record until I triggered index to invisible and then to visible

We are using Oracle 11g, 11.2.0.3. We know a record exists in a table but a select is not returning it for some odd reason. The execution plans the general query, not forcing any index, shows that ...
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How can I get rid of the “No Join Predicate” warning

I have this fairly straight-forward snippet of a query: DECLARE @ClientGUID numeric(16) = 9000011916900200; SELECT ch.GUID, c.LastName, c.FirstName, mrn.ClientIDCode AS MRN FROM Client c INNER ...