Posted on

Oracle DB: Statistics on Load

There are several changes that arrive with the optimizer when you move to 12c and above. There are changes to histograms, all of the adaptive features etc, but also, one of the simplest but coolest optimizer improvements when it comes to loading data. When you perform a direct-path insert into an empty table, or a create-table-as-select (CTAS) operation, there is no need to perform an additional DBMS_STATS call to gather statistics at the conclusion of the load. The load process itself handles that for you. Here’s a simple example of that in action:

PLSQL


Of course, many people are now aware of this functionality, so why does it warrant a blog post? Mainly to make readers aware of a boundary case. If the table you are creating or loading is an index-organized table (IOT), then you do not get the statistics gathered automatically.

Posted on

Main Uses for Couchbase Primary Index

 FROM customer USE KEYS ["cx:123"] Couchbase is a distributed database. It supports a flexible data model using JSON. Each document in a bucket will have a user-generated unique document key. This uniqueness is enforced during the insertion or updation of the data. Here’s an example document.

select meta().id, travel
from `travel-sample` travel
where type = 'airline' limit 1;
[
  {
      "id": "airline_10",
      "travel": {
          "callsign": "MILE-AIR",
          "country": "United States",
          "iata": "Q5",
          "icao": "MLA",
          "id": 10,
          "name": "40-Mile Air",
          "type": "airline"
          }
      }
  ]



INSERT INTO customer (key, value) VALUES(“cx:123”, {“name”:”joe”, “zip”: 94040, “state”:ca});

SELECT META().id FROM customer;

cx:123