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POComparing all individual records from two VERY similar tables with lots of data
 

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  1. POComparing all individual records from two VERY similar tables with lots of data
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    <p>I am developing a tool for enhancing part of the regression testing process.</p> <p><strong>What I need to achieve:</strong></p> <p>I have two tables both with about 7 thousand records. One is a snapshot from production, the other one represents the exactly same records that will be implemented after the update. </p> <p>Each record contains 50-200 fields of varying length. Two (field_1 and field_2) of these fields serve as identifiers to distinguish the records. Field 1 is used ti pair a record from production to a record from update, field 2 is used to identify the form of the message.</p> <p>For record from production there is always one and only one record with equal field_1 and field_2 values.</p> <p>I would like to write either a query, or code that will ( in few seconds at most ) return an array in the following or similar form:</p> <pre><code>Array ( [0] =&gt; Array ( [Production] =&gt; Array ( [id] =&gt; 83 [field1] =&gt; value1 [field2] =&gt; value2 [field3] =&gt; differing_val [field4] =&gt; value3 ..... ) [Update] =&gt; Array ( [id] =&gt; 1 [field1] =&gt; value1 [field2] =&gt; value2 [field3] =&gt; some_other_different_val [field4] =&gt; value3 ..... ) ) ) </code></pre> <p><strong>The problem:</strong></p> <ol> <li>I tried to take all records and build this dynamically ( execution didn't even finish after 10 minutes ), with some limit and pagination, it was better</li> <li>So I wrote this sql statement, that would do part of the job for me, but even with limit for some values it takes 5-7 minutes to finish (and it only does part of the job for me)</li> </ol> <p>Here is my sql query:</p> <pre><code>SELECT production_records.* FROM production_records WHERE production_records.token_2 = ( SELECT update_records.token_2 FROM update_records WHERE update_records.token_1 = production_records.token_1 AND update_records.token_2 = production_records.token_2 AND update_records.token_130 &lt;&gt; production_records.token_130 ) ORDER BY production_records.token_1 DESC LIMIT 6 </code></pre> <p>Here I know there are 6 differences, therefore the limit and still it takes 406 seconds.</p> <p><strong>Question:</strong></p> <p>Do you see anything, that could be done with the data, or sql to make it run faster? I'm not that good with sql yet, so I guess there lies the problem.</p> <p>I have full control over the data, so I can change anything, didn't come up yet with a better than O(n^2) solution.</p>
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    1. USIgor L.
    1. USIgor L.
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      1. POComparing all individual records from two VERY similar tables with lots of data
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      1. VTUpMod
    1. COIn terms of performance, it is generally much faster to use pure SQL. You should be able to accomplish this with a pretty simple SQL JOIN statement. `SELECT prod_name, supplier_name, supplier_address FROM product, suppliers WHERE (product.supplier_id = suppliers.supplier_id);` - Take a look at http://www.techotopia.com/index.php/Joining_Tables_in_MySQL
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      1. USMat Carlson
    2. COIf indeed the 2 dbs (A, B) start off the same, did you consider logging the diffs that db B is then asked to action?
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      1. USCups
    3. CO@matcarlson: thank you, will use joins.
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      1. USIgor L.
 

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