How does SQLite control access to the database?
SQLite uses reader/writer locks to control access to the database. (Under Win95/98/ME which lacks support for reader/writer locks, a probabilistic simulation is used instead.) But use caution: this locking mechanism might not work correctly if the database file is kept on an NFS filesystem.
How does SQLite allow multiple processes to read the same database at once?
SQLite allows multiple processes to have the database file open at once, and for multiple processes to read the database at once. When any process wants to write, it must lock the entire database file for the duration of its update. But that normally only takes a few milliseconds.
Is the precompiled version of SQLite threadsafe?
SQLite is threadsafe. We make this concession since many users choose to ignore the advice given in the previous paragraph. But in order to be thread-safe, SQLite must be compiled with the SQLITE_THREADSAFE preprocessor macro set to 1. Both the Windows and Linux precompiled binaries in the distribution are compiled this way.
Can a root user write on a file?
As in the title I cannot write on this file even though I am logged as root. Do you know how I can write the file? 1.) Who is the actual ‘owner’ of the file. 2.) Perhaps the file cannot be edited while it is in use? 3.7. Active-State Power Management Red Hat Enterprise Linux 7 | Red Hat Customer Portal
Do you have to enforce unique constraint in SQLite?
The SQL standard requires that a UNIQUE constraint be enforced even if one or more of the columns in the constraint are NULL, but SQLite does not do this. Isn’t that a bug? What is the Export Control Classification Number (ECCN) for SQLite?
What happens when you delete data from SQL Server?
In MS SQL server, when you delete data from the database, the database file (.MDF) does not automatically become smaller. This is by design. Increasing the size of the database then shrinking all the time is inefficient. In an ideal world – you’d create your DB with plenty of free space to grow into.
Is there a way to make a SQLite database in memory?
The most common way to force an SQLite database to exist purely in memory is to open the database using the special filename ” :memory: “. In other words, instead of passing the name of a real disk file into one of the sqlite3_open (), sqlite3_open16 (), or sqlite3_open_v2 () functions, pass in the string “:memory:”.
Can a process do select at the same time in SQLite?
Multiple processes can be doing a SELECT at the same time. But only one process can be making changes to the database at any moment in time, however. SQLite uses reader/writer locks to control access to the database.
How is a temporary database created in SQLite?
When the name of the database file handed to sqlite3_open () or to ATTACH is an empty string, then a new temporary file is created to hold the database. A different temporary file is created each time, so that just like as with the special “:memory:” string, two database connections to temporary databases each have their own private database.