HOW TO CHOOSE SS TABLES TO COMPACT SSTables are separated by density leveling in levels determined by the fan factors of the compaction setup. The amount of SSTables on a level, however, cannot be used as a trigger because there may be non-overlapping SSTables, unlike… Read More
STRATEGIES OF COMPACTION ▪️ Unified Compaction Strategy (UCS) ▪️ Size-Tiered Compaction Strategy (STCS) ▪️ Leveled Compaction Strategy (LCS) ▪️ Time Window Compaction Strategy (TWCS) UNIFIED COMPACTION STRATEGY: For the majority of workloads, including mixed read-write, time-series, read-heavy, and write-heavy workloads, the UnifiedCompactionStrategy (UCS) is… Read More
CHANGE DATA CAPTURE When a configurable size-on-disk for the CDC log is reached, Change Data Capture (CDC) offers a technique to refuse writes to certain tables and flag them for archiving. By setting the table property cdc=true (either when creating the table or modifying it),… Read More
APACHE CASSANDRA INSTALLATIONS These are the guidelines for setting up the supported Apache Cassandra releases on Linux systems. Cassandra runs on a wide array of Linux distributions including (but not limited to): ⦁ Ubuntu, most notably LTS releases 16.04 to 18.04. ⦁ CentOS & RedHat… Read More
BLOOM FILTERS WHAT ARE BLOOM FILTERS: Cassandra combines data from RAM (in memtables) and disk (in SSTables) in the read path. Cassandra uses a data structure called a bloom filter to avoid having to go through each and every SSTable data file to find the… Read More
CASSANDRA BACKUPS WHAT ARE BACKUPS: Immutable SSTable files are used by Apache Cassandra to store data. The backup copies of the database data that are kept as SSTable files in the Apache Cassandra database are called backups. There are various uses for backups, some of… Read More
USER DEFINED DATA TYPES IN CQL Handling several fields of connected data in a table is made easier with the use of a user-defined type. By representing the linked fields of information using a user-defined type rather than storing them in separate tables, applications that… Read More
DATATYPES IN CQL (2.0) CUSTOM DATA TYPE: A Custom datatype is defined by every Java class that extends the server-side Abstract Type class and can be loaded by Cassandra is called a custom type; as a result, it should be included in the CLASSPATH of every… Read More
COLLECTION DATATYPES IN CQL Collections are designed to store and denormalize modest amounts of data. They are useful for things like “labels applied to an email,” “the phone numbers of a given user,” and so on. However, collections are inappropriate in situations when items are… Read More
DATA TYPES IN CQL The Cassandra Query Language, or CQL, is supported by Apache Cassandra. Cassandra Apache The categories of data known as data types specify the kinds of data that can be kept in a variable or object. Programmers instruct the compiler on how… Read More
