Cache Interview Questions : Part 1

  1. What is BLOB caching ?

Ans : BLOBs that are stored in table rows use the same buffer caching rules as the tabular row, as they reside in the same data block as the rows. By default, BLOBs stored out of the row use

direct path reads and writes to store and retrieve data without caching.


  1. Do you recommend BLOB Removal ?

Ans : Database tables which are the target for Rule-Declare-Index rules are candidates for optimization by removing the pzPvStream (BLOB) column. For example, if workparties are used in work items and no customization is required, removing the pzPvStream column from the pc_index_workparty table can improve system performance.


  1. Where cache are stored ?

Ans : Most caches are stored in the system memory (JVM) or on disk


  1. What is rule cache ?

Ans : Rule cache holds data about the reads done from the PegaRULES database for rule classes.  If the data is available in the database, the system retrieves the rule, stores it in the Rule cache, and then sends the rule information back to whichever process requested it. The next time


  1. What if rule cahce is not tuned properly?

Ans : An incorrectly sized Rules cache may bog down memory resources


  1. What is rule assembly cache ?

Ans : Rules Assembly cache is used to minimize Java code generation and compilation mainly by tracking RuleSet lists and user entrie.


  1. What is the significance of proper tuning of Rule assembly cache ?

Ans : An improperly sized Rules Assembly cache can lead to repetitive and,sometimes, continuous rules assembly.


  1. What is Conclusion cache ?

Ans : Part of Dictionary cache .  contains instances of Java objects (resulting from the Rules Assembly process) that were generated, instantiated, and then persisted to the database for future use


  1. What is Property Definition cache

Ans : It is a cache of all the Rule-Obj-Property instances used by the system. This cache enhances system efficiency because properties are looked up frequently.


  1. Name few caches stored in memory ?

Ans : Rule Cache, Rule Assembly Cache, Dictionary Cache.


  1. Name few cache that stored in Disk ?

Ans : LookupList cache and Static content cache.


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