Imagine two different kinds of crossroads. One has traffic lights or police officers regulating traffic, motion on the crossroad is at limited speed, and there’s a watchdog registering precisely what car drove on the crossroad at what time precisely, and what direction it went. The other has none of that and everyone who arrives at … Read more
I am Max, the PMM of DataGrip. We usually say that DataGrip provides the same functionality as all the other IDE’s from JetBrains with the database support. As mentioned above, DataGrip provides better user experience as a standalone IDE.
Scala: If all you need is unique numbers you can use zipWithUniqueId and recreate DataFrame. First some imports and dummy data: import sqlContext.implicits._ import org.apache.spark.sql.Row import org.apache.spark.sql.types.{StructType, StructField, LongType} val df = sc.parallelize(Seq( (“a”, -1.0), (“b”, -2.0), (“c”, -3.0))).toDF(“foo”, “bar”) Extract schema for further usage: val schema = df.schema Add id field: val rows = … Read more
Atomicity – a transaction to transfer funds from one account to another involves making a withdrawal operation from the first account and a deposit operation on the second. If the deposit operation failed, you don’t want the withdrawal operation to happen either. Consistency – a database tracking a checking account may only allow unique check … Read more
If SQLite is compiled with SQLITE_ENABLE_DBSTAT_VTAB, you can query the dbstat table. This should return the table size (in bytes) of table TABLENAME: SELECT SUM(“pgsize”) FROM “dbstat” WHERE name=”TABLENAME”; https://www.sqlite.org/dbstat.html This is what is used by the sqlite3_anazlyer CLI tool, which can also be used for this purpose.
If it were dangerous, Stack Overflow wouldn’t be displaying user IDs in their URLs in order to make user profile lookups work: https://stackoverflow.com/users/104826/rfactor Edit of seriousness of immense levels: if user IDs are themselves sensitive data; for example your primary keys for some reason happen to be social security numbers, that’ll definitely be a security … Read more
Windows Vista or later: C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\databases Windows XP: C:\Documents and Settings\%USERNAME%\Application Support\Google\Chrome\Default\databases Windows 10: C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\History Mac OS X (and macOS—sub-path changes between versions but are all under this main path): ~/Library/Application Support/Google/Chrome/* Linux: ~/.config/google-chrome/Default/databases
http://sqlite.org/whentouse.html explains “Situations Where Another RDBMS May Work Better”: SQLite uses reader/writer locks on the entire database file. That means if any process is reading from any part of the database, all other processes are prevented from writing any other part of the database. Similarly, if any one process is writing to the database, all … Read more
A better representation of a bitmap index, is if given the sample above: Identifier Gender RowID 1 Female R1 2 Male R2 3 Male R3 4 Unspecified R4 5 Female R5 the a bitmap index on the gender column would (conceptually) look like this: Gender R1 R2 R3 R4 R5 Female 1 0 0 0 … Read more