Mercurial > gemma
view pkg/xlsx/sql.go @ 5520:05db984d3db1
Improve performance of bottleneck area calculation
Avoid buffer calculations by replacing them with simple distance comparisons
and calculate the boundary of the result geometry only once per iteration.
In some edge cases with very large numbers of iterations, this reduced
the runtime of a bottleneck import by a factor of more than twenty.
author | Tom Gottfried <tom@intevation.de> |
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date | Thu, 21 Oct 2021 19:50:39 +0200 |
parents | 979f139cde4d |
children | 6270951dda28 |
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// This is Free Software under GNU Affero General Public License v >= 3.0 // without warranty, see README.md and license for details. // // SPDX-License-Identifier: AGPL-3.0-or-later // License-Filename: LICENSES/AGPL-3.0.txt // // Copyright (C) 2021 by via donau // – Österreichische Wasserstraßen-Gesellschaft mbH // Software engineering by Intevation GmbH // // Author(s): // * Sascha L. Teichmann <sascha.teichmann@intevation.de> package xlsx import ( "context" "database/sql" "fmt" "strconv" "strings" ) type sqlResult struct { columns []string rows [][]interface{} } func (sr *sqlResult) find(column string) int { for i, name := range sr.columns { if name == column { return i } } return -1 } func replaceStmt(stmt string) (string, []string) { var names []string add := func(name string) int { for i, n := range names { if n == name { return i + 1 } } names = append(names, name) return len(names) } replace := func(s string) string { n := add(strings.TrimSpace(s)) return "$" + strconv.Itoa(n) } out := handlebars(stmt, replace) return out, names } func query( ctx context.Context, tx *sql.Tx, stmt string, eval func(string) (interface{}, error), ) (*sqlResult, error) { nstmt, nargs := replaceStmt(stmt) args := make([]interface{}, len(nargs)) for i, n := range nargs { var err error if args[i], err = eval(n); err != nil { return nil, err } } rs, err := tx.QueryContext(ctx, nstmt, args...) if err != nil { return nil, fmt.Errorf("SQL failed: '%s': %v", nstmt, err) } defer rs.Close() columns, err := rs.Columns() if err != nil { return nil, err } var rows [][]interface{} ptrs := make([]interface{}, len(columns)) for rs.Next() { row := make([]interface{}, len(columns)) for i := range row { ptrs[i] = &row[i] } if err := rs.Scan(ptrs...); err != nil { return nil, err } rows = append(rows, row) } if err := rs.Err(); err != nil { return nil, err } return &sqlResult{ columns: columns, rows: rows, }, nil }