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author | Alex Tatiyants <atatiyan@gmail.com> | 2016-01-04 21:32:55 -0800 |
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committer | Alex Tatiyants <atatiyan@gmail.com> | 2016-01-04 21:32:55 -0800 |
commit | 9554ab8c51c0a5853a58be98936223908eabcbb9 (patch) | |
tree | 5a6635bbaecabd593981a71ca6ce63632482903a /app/services/help-service.ts | |
parent | d89ddcf3532937d395898f255c42f3d26303f1c4 (diff) |
add node descriptions, clean up plan-node.ts
Diffstat (limited to 'app/services/help-service.ts')
-rw-r--r-- | app/services/help-service.ts | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/app/services/help-service.ts b/app/services/help-service.ts new file mode 100644 index 0000000..11bb4c0 --- /dev/null +++ b/app/services/help-service.ts @@ -0,0 +1,27 @@ +/// <reference path="lodash.d.ts" /> + +export class HelpService { + getNodeTypeDescription(nodeType: string) { + return NODE_DESCRIPTIONS[nodeType.toUpperCase()]; + } +} + +export var NODE_DESCRIPTIONS = { + "LIMIT":"returns a specified number of rows from a record set.", + "SORT": "sorts a record set based on the specified sort key.", + "NESTED LOOP": `merges two record sets by looping through every record in the first set and + tries to find a match in the second set. All matching records are returned.`, + "MERGE JOIN": `merges two record sets by first sorting them on a <strong>join key</strong>.`, + "AGGREGATE": `groups records together based on a GROUP BY or aggregate function (like <code>sum()</code>).`, + "HASHAGGREGATE": `groups records together based on a GROUP BY or aggregate function (like sum()). Hash Aggregate uses + a hash to first organize the records by a key.`, + "SEQ SCAN": `finds relevant records by sequentially scanning the table. Seq Scans perform a single read operation + (only the table is read).`, + "INDEX SCAN": `finds relevant records based on an <strong>Index</strong>. Index Scans perform 2 read operations: one to + read the index and another to read the actual value from the table.`, + "INDEX ONLY SCAN": `finds relevant records based on an <strong>Index</strong>. Index Only Scans perform a single read operation + from the index and do not read from the corresponding table.`, + "BITMAP HEAP SCAN": "scans all pages returned by the <strong>Bitmap Index Scan</strong> for relevant rows.", + "BITMAP INDEX SCAN": `uses a <strong>Bitmap Index</strong> (index which uses 1 bit per page) to find all relevant pages. + Results of this node are fed to the <strong>Bitmap Heap Scan</strong>.` +} |