The connection knows which tables it can reach, which columns they have and what it has been doing, and it makes all of that available as tables. Where [[Invantive Query Tool/Available Objects|Available Objects]] and [[Invantive Query Tool/Describe Object|Describe Object]] show that by clicking, the data dictionary lets it be asked for as a statement - and a statement can be filtered, joined, exported and repeated. ## Asking It Something The tables live in the `DataDictionary` container, which every connection carries; see [[Invantive Query Tool/Built-in Drivers|Built-in Drivers]]. Two of them answer most questions: ```sql select catalog , schema , name from SystemTables@DataDictionary where lower(name) like '%project%' order by name ``` Eight tables of the sample database hold the word: ![[20260904-qt-data-dictionary.png]] `SystemTableColumns@DataDictionary` does the same for the columns, and joining the two lists the columns of everything whose name holds a word. From there the ordinary tools apply: a `where`, a join, a count per container, an export. ## What Else Is In There Beside the catalogue, the dictionary holds what this session has done: the calls it made, the rows it changed, what it downloaded and what it measured. `SessionIOs@DataDictionary` is the same record the [[Invantive Query Tool/Connection Monitor|Connection Monitor]] shows in a window, which means a question the window cannot answer can be written as a statement instead - the ten slowest calls, the traffic per table, everything which failed with one message code. It also holds a handful of tables which exist to be useful in a statement rather than to describe anything: `Dual@DataDictionary` for a statement without a table, `Range@DataDictionary` for a series of numbers, `Calendar@DataDictionary` for a series of dates. ## Where It Is Documented Every table of the dictionary has a page of its own under [[Invantive UniversalSQL/Service Drivers/Data Dictionary Data Model/Data Model|Data Dictionary Data Model]], with its columns and their meaning.