103 lines
4.4 KiB
JavaScript
103 lines
4.4 KiB
JavaScript
/**
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* Returns template function (function that accepts template parameters and returns a string)
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*/
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module.exports = (options) => {
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let templateFn = aggregationQueryTemplates[options.placement];
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if (!templateFn) {
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throw new Error("Invalid Aggregation placement: '" + options.placement + "'");
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}
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return templateFn;
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};
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const aggregate_columns = ctx => {
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let columns = ctx.columns || {};
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if (Object.keys(columns).length == 0) {
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// default aggregation
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columns = {
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_cdb_feature_count: {
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aggregate_function: 'count'
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}
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}
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}
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return Object.keys(columns).map(column_name => {
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let aggregate_expression = columns[column_name].aggregate_expression;
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if (!aggregate_expression) {
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const aggregate_function = columns[column_name].aggregate_function || 'count';
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const aggregated_column = columns[column_name].aggregated_column || '*';
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aggregate_expression = `${aggregate_function}(${aggregated_column})`;
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}
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return `${aggregate_expression} AS ${column_name}`;
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}).join(', ');
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};
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// Notes:
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// * ${ctx.res*0.00028/256}*!scale_denominator! is equivalent to ${ctx.res/256}*CDB_XYZ_Resolution(CDB_ZoomFromScale(!scale_denominator!))
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// * We need to filter spatially using !bbox! to make the queries efficient because the filter added by Mapnik (wrapping the query)
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// is only applied after the aggregation.
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// * This queries are used for rendering and the_geom is omitted in the results for better performance
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const aggregationQueryTemplates = {
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'centroid': ctx => `
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WITH _cdb_params AS (
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SELECT
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(${ctx.res*0.00028/256}*!scale_denominator!)::double precision AS res,
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!bbox! AS bbox
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)
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SELECT
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row_number() over() AS cartodb_id,
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ST_SetSRID(
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ST_MakePoint(
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AVG(ST_X(_cdb_query.the_geom_webmercator)),
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AVG(ST_Y(_cdb_query.the_geom_webmercator))
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), 3857
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) AS the_geom_webmercator,
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${aggregate_columns(ctx)}
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FROM (${ctx.sourceQuery}) _cdb_query, _cdb_params
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WHERE _cdb_query.the_geom_webmercator && _cdb_params.bbox
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GROUP BY Floor(ST_X(_cdb_query.the_geom_webmercator)/_cdb_params.res), Floor(ST_Y(_cdb_query.the_geom_webmercator)/_cdb_params.res)
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`,
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'point-grid': ctx => `
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WITH _cdb_params AS (
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SELECT
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(${ctx.res*0.00028/256}*!scale_denominator!)::double precision AS res,
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!bbox! AS bbox
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),
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_cdb_clusters AS (
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SELECT
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ST_SetSRID(ST_MakePoint(AVG(ST_X(_cdb_query.the_geom_webmercator)), AVG(ST_Y(_cdb_query.the_geom_webmercator))), 3857) AS the_geom_webmercator,
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Floor(ST_X(_cdb_query.the_geom_webmercator)/_cdb_params.res)::int AS _cdb_gx,
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Floor(ST_Y(_cdb_query.the_geom_webmercator)/_cdb_params.res)::int AS _cdb_gy,
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${aggregate_columns(ctx)}
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FROM (${ctx.sourceQuery}) _cdb_query, _cdb_params
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WHERE the_geom_webmercator && _cdb_params.bbox
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GROUP BY _cdb_gx, _cdb_gy
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)
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SELECT
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ST_SetSRID(ST_MakePoint(_cdb_gx*(res+0.5), _cdb_gy*(res*0.5)), 3857) AS the_geom_webmercator,
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_cdb_feature_count
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FROM _cdb_clusters, _cdb_params
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`,
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'point-sample': ctx => `
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WITH _cdb_params AS (
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SELECT
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(${ctx.res*0.00028/256}*!scale_denominator!)::double precision AS res,
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!bbox! AS bbox
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), _cdb_clusters AS (
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SELECT
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MIN(cartodb_id) AS cartodb_id,
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${aggregate_columns(ctx)}
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FROM (${ctx.sourceQuery}) _cdb_query, _cdb_params
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WHERE _cdb_query.the_geom_webmercator && _cdb_params.bbox
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GROUP BY Floor(ST_X(_cdb_query.the_geom_webmercator)/_cdb_params.res), Floor(ST_Y(_cdb_query.the_geom_webmercator)/_cdb_params.res)
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) SELECT
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_cdb_clusters.cartodb_id,
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the_geom, the_geom_webmercator,
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_cdb_feature_count
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FROM _cdb_clusters INNER JOIN (${ctx.sourceQuery}) _cdb_query on (_cdb_clusters.cartodb_id = _cdb_query.cartodb_id)
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`
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};
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