Search results
Results from the WOW.Com Content Network
Regular expressions (or regex) are a common and very versatile programming technique for manipulating strings. On Wikipedia you can use a limited version of regex called a Lua pattern to select and modify bits of text from a string. The pattern is a piece of code describing what you are looking for in the string.
DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of: database link; DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo. All of this takes time, hence it takes time much longer than with TRUNCATE
A table is a sequence, optionally supplemented by named keys: digit["two"]="2". Several table functions like table.concat will only work with the numbered values and ignore named keys. The metatable offers a large, optional set of methods for altering table behavior. For example, you can define a table to be callable like a function.
The string-search functions in Lua script can run extremely fast, comparing millions of characters per second. For example, a search of a 40,000-character article text, for 99 separate words (passed as 99 parameters in a template), ran within one second of Lua CPU clock time.
Later it was used to refer to a subset of Structured Query Language (SQL) for declaring tables, columns, data types and constraints. SQL-92 introduced a schema manipulation language and schema information tables to query schemas. [2] These information tables were specified as SQL/Schemata in SQL:2003.
This help-page, Help:Lua debugging, explains issues of writing Lua script and debugging the source code, to remove errors or improve performance. Because Lua is a "semi-compiled" interpreted language, it does not prescreen for all common syntax errors, nor detect misspelled variables, which are only found at runtime when seeing the " Script ...
Also, all Lua in the page is limited to 10 seconds CPU time (you can look in the source code of a rendered page to see how long a template or module took to parse). And relative to standard Lua, Scribunto's Lua lacks all sorts of functions (see mw:Extension:Scribunto/Lua reference manual § Differences from standard Lua).
Lua provides functions to push and pop most simple C data types (integers, floats, etc.) to and from the stack, and functions to manipulate tables through the stack. The Lua stack is somewhat different from a traditional stack; the stack can be indexed directly, for example. Negative indices indicate offsets from the top of the stack.