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For Example:
Code Block | ||||
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explain query plan select * from household where FWHOHFNAME LIKE '%abc%' |
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*Application.java → Add the register table names
Code Block language java theme Eclipse private String[] getFtsTables(){ String[] ftsTables = { "household" ... }; return ftsTables; }
Add search and sort fields
Code Block language java theme Eclipse private String[] getFtsSearchFields(String tableName){ if(tableName.equals("household")){ String[] ftsSearchFiledsftsSearchFields = { "FWHOHFNAME", "FWGOBHHID", "FWJIVHHID" ... }; return ftsSearchFiledsftsSearchFields; } ... } private String[] getFtsSortFields(String tableName){ if(tableName.equals("household")) { String[] sortFields = {"FWHOHFNAME", "FWGOBHHID", "FWJIVHHID" ... }; return sortFields; } ... return null; }
Add condition fields If your query has a main condition
For Example:
Code Block language java theme Eclipse queryBUilder.mainCondition(" FWHOHFNAME is not null ");
Code Block language java theme Eclipse private String[] getFtsMainConditions(String tableName){ if(tableName.equals("household")) { String[] sortFields = {"FWHOHFNAME"}; return sortFields; } ... }
In *Application.onCreate(), update the global context instance i.e. update context.commonFtsObject
Code Block language java theme Eclipse context.updateCommonFtsObject(createCommonFtsObject());
Code Block language java theme Eclipse private CommonFtsObject createCommonFtsObject(){ CommonFtsObject commonFtsObject = new CommonFtsObject(getFtsTables()); for(String ftsTable: commonFtsObject.getTables()){ commonFtsObject.updateSearchFields(ftsTable, getFtsSearchFields(ftsTable)); commonFtsObject.updateSortFields(ftsTable, getFtsSortFields(ftsTable)); commonFtsObject.updateMainConditions(ftsTable, getFtsMainConditions(ftsTable)); } return commonFtsObject; }
In org.ei.opensrp.commonregistry.CommonRepository#onCreate, id and relationalid indexes are created for each common repository table.
Code Block language java theme Eclipse if(StringUtils.isNotBlank(common_ID_INDEX_SQL)) { database.execSQL(common_ID_INDEX_SQL); } if(StringUtils.isNotBlank(common_Relational_ID_INDEX_SQL)) { database.execSQL(common_Relational_ID_INDEX_SQL); }
In org.ei.opensrp.Context.java, commonFtsObject is passed as an argument when initializing the Repository class.
Code Block language java theme Eclipse if(commonFtsObject != null){ repository = new Repository(this.applicationContext, session(), this.commonFtsObject, drishtireposotoryarray); }
Then the virtual tables are created in org.ei.opensrp.repository.Repository#onCreate, after the database has been created.
Code Block language java theme Eclipse if(this.commonFtsObject != null) { for (String ftsTable: commonFtsObject.getTables()) { Set<String> searchColumns = new LinkedHashSet<String>(); searchColumns.add(CommonFtsObject.idColumn); searchColumns.add(CommonFtsObject.relationalIdColumn); searchColumns.add(CommonFtsObject.phraseColumnName); String[] mainConditions = this.commonFtsObject.getMainConditions(ftsTable); if(mainConditions != null) for (String mainCondition : mainConditions) { searchColumns.add(mainCondition); } String[] sortFields = this.commonFtsObject.getSortFields(ftsTable); if(sortFields != null) for (String sortValue : sortFields) { searchColumns.add(sortValue); } String joinedSearchColumns = StringUtils.join(searchColumns, ","); String searchSql = "create virtual table " + CommonFtsObject.searchTableName(ftsTable) + " using fts4 (" + joinedSearchColumns + ");"; database.execSQL(searchSql); } }
These virtual tables are updated after saving a form submission.
For Example, in FormSubmissionService.java:
Code Block language java theme Eclipse ziggyService.saveForm(getParams(submission), submission.instance()); // Update FTS Tables updateFTSsearch(submission);
- Update filterandSortExecute() and CountExecute() methods to use FTS search
Perform search/sort query in the virtual table(s) and return the reference ids
Full Virtual table scans are optimized and therefore faster than normal table scans.
Code Block language sql title Explain query plan explain query plan select object_id from household_search where phrase match 'abc*'
Returns
Virtual table full scans are optimizedselectid order from detail 0 0 0 SCAN TABLE household_search VIRTUAL TABLE INDEX 4: Use the ids in Step 7(a) above to filter the main query
Since id fields are indexed, Step 5, there are no full table scans, only virtual table scans.
Code Block language sql title Explain query plan explain query plan select * from household where id in (select object_id from household_search where phrase match 'abc*')
Returns
selectid order from detail 0 0 0 SEARCH TABLE household USING INDEX sqlite_autoindex_household_1 (id=?) 0 0 0 EXECUTE LIST SUBQUERY 1 0
0 0 SCAN TABLE household_search VIRTUAL TABLE INDEX 4:
Code Block language java theme Eclipse title Using FTS // Get the virtual table query String sql = sqb.searchQueryFts(tablename, joinTable, mainCondition, filters, Sortqueries, currentlimit, currentoffset); // Get the reference ids List<String> ids = commonRepository.findSearchIds(sql); // Update the main query by adding the reference ids in the where clause currentquery = sqb.toStringFts(ids, tablename + "." + CommonRepository.ID_COLUMN, Sortqueries); query = sqb.Endquery(currentquery);
FTS Table Structure
Facts
- Queries perform much faster when indexes are used.
- Indexes are ignored when SQLite's LIKE-keyword based query is used.
- Virtual tables require more space compared to regular tables.
- It takes more time to insert a record in a virtual table.
- Always consider
explain query plan
to determine whether your queries aren’t going to work slowly. - FTS does not support suffix search, only prefix.
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