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We can just convert LONG text into CLOB for further operations. Luckily we have CLOB which is a searchable column type. The first idea in my mind is to convert TEXT into something searchable. There're more explanations about solving ORA-00932. ORA-00932: inconsistent datatypes: expected CHAR got LONGĪs you can see, we cannot use LIKE to filter the column value.
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Select owner, view_name from all_views where upper(text) like '%NAME%' SQL> select owner, view_name from all_views where upper(text) like '%NAME%' order by 1,2 If you want to search TEXT column of VIEW, you should go for ALL_VIEWS.īut the thing is, the column TEXT in ALL_VIEWS is LONG which is a plain old text storing type, it cannot be searched.
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So in general, yes, you can go faster than regexes WHEN THE NEEDLES ARE CONSTANT.Dictionary view ALL_SOURCE contains only several object types like PROCEDURE, PACKAGE BODY, FUNCTION, TYPE except VIEW. You have four entries for each pattern (offsets of 0, 1, 2, and 3 from the start of the pattern) and then this way despite thousands of patterns in the table they only test one or two per 32-bit word in the subject line.
#Wamper server how to search files for text string code
It then does some simple hash code to fit the result into 12 bits, and then looks in a table to see if there's a hit. There's a spam-killer tool that looks at 32-bit machine words at a time. You still might want to make a DFSM but instead of calling a general search method, you call does_this_DFSM_match_at_this_offset().Īnother tactic is to test more than 8 bits at a time. When you have more than one needle, the construction and use of your table grows more complicated, but it still may possibly save you an order of magnitude on probes. The table entry will tell you (a) what leftward offset from the cursor that the needle might be found, or (b) that you can move the cursor len(needle) farther to the right. Now, position the cursor at len(needle)-1. Construct a table of all characters and the rightmost position that they appear in the needle (if at all). (Remember that for when you want to reuse your code.)Īnother tactic is to slide the cursor more than one character to the right if at all possible. However, Rabin-Karp was originally designed for a single needle, so you would need to support backtracking if one match could ever be a proper prefix of another. Rabin-Karp builds a DFSM out of the string (or strings) for which you are searching so that the test and the cursor motion are combined in a single operation. If the smallest needle is longer than a few characters, you may be able to do a little bit better than a generalized regex library.īasically all string searches work by testing for a match at the current position (cursor), and if none is found, then trying again with the cursor slid farther to the right. The best answer depends quite a bit on how many haystacks you have and the minimum size of a needle. Therefore, there's a good chance you can do better for your particular problem. The existence of a recursive/non-recursive distinction is a pretty strong suggestion that BOOST is not necessarily a linear-time discrete finite-state machine. Then reading x next will move me to the string 1 matched state etc., and any char other than xyz will move to the initial state, and I will not need to retract back to b. Not that I can program better than the boost guys, but perhaps a dedicated implementation is more efficient than a general one.Īs the strings stay constant over long time, I can afford building a data structure, like a state transition table, upfront.Į.g., if the strings are abcx, bcy and cz, and I've read so far abc, I should be in a combined state that means you're either 3 chars into string 1, 2 chars into string 2 or 1 char into string 1.
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The performance of this task is important, so I wonder if I can improve it. I am currently using boost regex matching with str1 | str2 |. Additional simplification is that none of the strings is contained in any other. The strings are constant for the whole session and are not many (~10). I need to search incoming not-very-long pieces of text for occurrences of given strings.