odbcsv new parameter max-str-len

Changelog.md

@@ -6,7 +6,7 @@
 * `TextColumn` is now generic over its character type. The type alias `CharColumn` for
   `TextColumn<u8>` can serve as a drop in replacement for the previous iteration of `TextColumn`.
 * `AnyColumnBuffer` has a new variant called `WText` holding a UTF-16 `TextColumn<u16>` or `WCharColumn`.
-* `TextRowSet::for_cursor` has a new parameter `max_str_limit` to designate the upper limit for column buffer size.
+* `TextRowSet::for_cursor` has a new parameter `max_str_len` to designate the upper limit for column buffer size.
 * Add `TextRowSet::indicator_at` to allow checking for truncation of strings.
 
 ## 0.17.0

odbc-api/src/buffers/text_column.rs

@@ -142,8 +142,7 @@ impl<C> TextColumn<C> {
                     new_value[..max_copy_length].clone_from_slice(&old_value[..max_copy_length]);
                 }
                 Indicator::Length(num_bytes_len) => {
-                    let num_bytes_to_copy =
-                        min(num_bytes_len / size_of::<C>(), max_copy_length);
+                    let num_bytes_to_copy = min(num_bytes_len / size_of::<C>(), max_copy_length);
                     new_value[..num_bytes_to_copy].copy_from_slice(&old_value[..num_bytes_to_copy]);
                 }
             }

odbc-api/src/buffers/text_row_set.rs

@@ -1,4 +1,4 @@
-use super::{Indicator, text_column::TextColumn};
+use super::{text_column::TextColumn, Indicator};
 use crate::{handles::Statement, Cursor, Error, ParameterCollection, RowSetBuffer};
 use std::{
     cmp::min,
@@ -109,7 +109,7 @@ impl TextRowSet {
     pub fn for_cursor(
         batch_size: u32,
         cursor: &impl Cursor,
-        max_str_limit: Option<usize>,
+        max_str_len: Option<usize>,
     ) -> Result<TextRowSet, Error> {
         let num_cols = cursor.num_result_cols()?;
         let buffers = (1..(num_cols + 1))
@@ -122,7 +122,7 @@ impl TextRowSet {
                         cursor.col_display_size(col_index as u16)? as usize
                     };
                 // Apply upper bound if specified
-                let max_str_len = max_str_limit
+                let max_str_len = max_str_len
                     .map(|limit| min(limit, reported_len))
                     .unwrap_or(reported_len);
                 Ok(TextColumn::new(batch_size as usize, max_str_len))

odbc-api/tests/integration.rs

@@ -4,7 +4,14 @@ use test_case::test_case;
 
 use common::{cursor_to_string, setup_empty_table, SingleColumnRowSetBuffer, ENV};
 
-use odbc_api::{ColumnDescription, Cursor, DataType, IntoParameter, Nullability, Nullable, U16String, buffers::{AnyColumnView, AnyColumnViewMut, BufferDescription, BufferKind, ColumnarRowSet, Indicator, TextRowSet}, parameter::VarChar32};
+use odbc_api::{
+    buffers::{
+        AnyColumnView, AnyColumnViewMut, BufferDescription, BufferKind, ColumnarRowSet, Indicator,
+        TextRowSet,
+    },
+    parameter::VarChar32,
+    ColumnDescription, Cursor, DataType, IntoParameter, Nullability, Nullable, U16String,
+};
 use std::{iter, thread};
 
 const MSSQL: &str =

odbcsv/Changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.3.15
+
+* New optional parameter `max-str-len` can be used to limit memory consumption.
+
 ## 0.3.14
 
 * Insert now logs batch number and rows

odbcsv/src/main.rs

@@ -65,6 +65,10 @@ struct QueryOpt {
     /// but require more memory during execution.
     #[structopt(long, default_value = "5000")]
     batch_size: u32,
+    /// Maximum string length in bytes. If ommitted no limit is applied and the ODBC driver is taken
+    /// for its word regarding the maximum length of the columns.
+    #[structopt(long, short = "m")]
+    max_str_len: Option<usize>,
     /// Path to the output csv file the returned values are going to be written to. If omitted the
     /// csv is going to be printed to standard out.
     #[structopt(long, short = "o")]
@@ -187,6 +191,7 @@ fn query(environment: &Environment, opt: &QueryOpt) -> Result<(), Error> {
         parameters,
         query,
         batch_size,
+        max_str_len,
     } = opt;
 
     // If an output file has been specified write to it, otherwise use stdout instead.
@@ -214,7 +219,7 @@ fn query(environment: &Environment, opt: &QueryOpt) -> Result<(), Error> {
             let headline: Vec<String> = cursor.column_names()?.collect::<Result<_, _>>()?;
             writer.write_record(headline)?;
 
-            let mut buffers = TextRowSet::for_cursor(*batch_size, &cursor, None)?;
+            let mut buffers = TextRowSet::for_cursor(*batch_size, &cursor, *max_str_len)?;
             let mut row_set_cursor = cursor.bind_buffer(&mut buffers)?;
 
             // Use this number to count the batches. Only used for logging.

odbcsv/tests/lib.rs

@@ -89,6 +89,30 @@ fn query_mssql() {
         .stdout(csv);
 }
 
+#[test]
+fn max_str_len() {
+    let csv = "title,year\n\
+        Jura,1993\n\
+        2001,1968\n\
+        Inte,\n\
+    ";
+
+    Command::cargo_bin("odbcsv")
+        .unwrap()
+        .args(&[
+            "-vvvv",
+            "query",
+            "--max-str-len",
+            "4",
+            "--connection-string",
+            MSSQL,
+            "SELECT title, year from Movies",
+        ])
+        .assert()
+        .success()
+        .stdout(csv);
+}
+
 #[test]
 fn placeholders() {
     let csv = "title\n\