When you call 'rollback', everything done since 'begin transaction' is undone. What then? SQL transactions to the rescue! What if all these inserts have to do with a single action (updating a user database, for example) but don't hit an error until tabler, and you need tabler or the user database is now invalid. Insert into tabler (k1, k2, k3) values ($k, $l, $m) Insert into tableb (x1, x2, x3) values ($a, $b, $c) Insert into tablea (f1, f2, f3) values ($x, $y, $z) You are already familiar with an SQL statement, see the example above.īut, the last option, an "sql transaction" is a feature of any ACID compliant database (such as PostgreSQL, of which I am fond, and which MySQL is gradually approaching in featureset) wherein you can wrap any number of sql statements into a single transaction.
You can use a single connection as many times as you want in a single web page hit to execute as many SQL statements as you like. They are all closely related, but aren't the same. Of course, you could perform this trick handily by simply modifying your sql statement, but I think this proves the point.Īnother issue to consider is what is a "transaction"? 90,000 transactions could be considered to be 90,000 database connections, or 90,000 SQL transactions, or 90,000 statements. Now, without ever using any more memory than required for a single row, we've weeded out all rows where importantfield is empty. this weeds out rows where importantfield is empty $sql="elect * from bignastytable where (some condition)" But, you have to process your information in chunks (typically, line by line) and write immediately to disk to keep memory usage to an absolute minimum.įor example, you could reduce memory usage by eliminating empty elements before you even consider putting them into an array. what you want to do can most certainly be done.
#Php array length limit code
The default is 8 MB, which means that code and data cannot occupy more than that amount of memory or your script barfs. PHP caps memory usage at a system-wide predefined value. However, since you're working in a shared environment, you'll likely run into issues with memory usage. There is no limit per se on the size of an array - I've run arrays in size over 100 MB without issues. I'd hate to code the whole blasted thing an find out it is impossible anyway! will I end up being limited by the size an array can be or the time it takes to process the PHP file before it times out. if I invest the time to code such a beast. I have decided that the only way to make this work with the limitations on the number of Mysql transactions i can have, is to load the data into php arrays and process it there, before sending it to the database. it eliminates most of these 102,834 records (due to duplicates and zero qnty items being removed) with a final result file of only about 19,000 items) I am nowhere close (as in multiply by 10 or more)! and with all the importing INSERT, SELECT, UPDATE, and DELETE mysql commands that must take place for each record during the parsing. my script will not work (The total rows of all three files I am importing comes to 102,834 records.
and I just found out that due to the fact that the web hosting company allows a maximum of 90,000 mysql transactions per hour. This is going to be hosted on an off site server account (not an internal company server). which will be their online inventory and a source to output CSV files from. then another program that does the match, merge, pear-down and output of the data to another final table. I created PHP programs to parse and upload the raw data into tables in mysql. I wrote some PHP code and setup a mysql database to help a company that needed to take data from their inventory and merge it with inventory data from two suppliers (match similar part numbers in each file to add inventory quantities together an then eliminate zero quantity items to create datafiles for distribution.). I need to know if there is any limit (or at least a practical limit) to the size that a PHP array can be.
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