diff options
Diffstat (limited to 'app/services/help-service.ts')
-rw-r--r-- | app/services/help-service.ts | 28 |
1 files changed, 14 insertions, 14 deletions
diff --git a/app/services/help-service.ts b/app/services/help-service.ts index 0195aff..6067b05 100644 --- a/app/services/help-service.ts +++ b/app/services/help-service.ts @@ -7,24 +7,24 @@ export class HelpService { } 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 + '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 trying 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>.`, - "HASH": `generates a hash table from the records in the input recordset. Hash is used by + 'MERGE JOIN': `merges two record sets by first sorting them on a <strong>join key</strong>.`, + 'HASH': `generates a hash table from the records in the input recordset. Hash is used by <strong>Hash Join</strong>.`, - "HASH JOIN": `joins to record sets by hashing one of them (using a <strong>Hash Scan</scan>).`, - "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 + 'HASH JOIN': `joins to record sets by hashing one of them (using a <strong>Hash Scan</scan>).`, + '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 input record set. When reading from a table, + 'SEQ SCAN': `finds relevant records by sequentially scanning the input record set. When reading from a table, Seq Scans (unlike Index 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 + '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 + '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": "searches through the 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. + 'BITMAP HEAP SCAN': 'searches through the 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>.` -} +}; |