diff --git a/polars_bio/__init__.py b/polars_bio/__init__.py
index 3c84add..4b83d78 100644
--- a/polars_bio/__init__.py
+++ b/polars_bio/__init__.py
@@ -1 +1 @@
-from .overlap import overlap
+from .overlap import overlap, ctx
diff --git a/polars_bio/overlap.py b/polars_bio/overlap.py
index f06b8da..aac792b 100644
--- a/polars_bio/overlap.py
+++ b/polars_bio/overlap.py
@@ -9,13 +9,27 @@
 import pyarrow.compute as pc
 from polars.io.plugins import register_io_source
 from typing_extensions import TYPE_CHECKING, Union
+from .polars_bio import overlap_scan, overlap_frame
+from .polars_bio import BioSessionContext
 
+def singleton(cls):
+    """Decorator to make a class a singleton."""
+    instances = {}
 
-from .polars_bio import overlap_scan, overlap_frame
+    def get_instance(*args, **kwargs):
+        if cls not in instances:
+            instances[cls] = cls(*args, **kwargs)
+        return instances[cls]
+
+    return get_instance
+
+@singleton
+class Context:
+    def __init__(self):
+        self.ctx = BioSessionContext()
+        self.ctx.set_option("datafusion.execution.target_partitions", "1")
 
-from .polars_bio import BioSessionContext
 
-ctx = BioSessionContext()
 
 
 if TYPE_CHECKING:
@@ -24,6 +38,7 @@
 
 DEFAULT_INTERVAL_COLUMNS = ["contig", "pos_start", "pos_end"]
 
+ctx = Context().ctx
 
 def overlap(df1 : Union[str, pl.DataFrame, pl.LazyFrame, pd.DataFrame],
             df2 : Union[str, pl.DataFrame, pl.LazyFrame, pd.DataFrame],
diff --git a/src/lib.rs b/src/lib.rs
index 0475ede..4623efb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,7 +5,8 @@ use datafusion::arrow::array::{ArrayData, RecordBatch};
 use datafusion::arrow::error::ArrowError;
 use datafusion::arrow::ffi_stream::ArrowArrayStreamReader;
 use datafusion::arrow::pyarrow::PyArrowType;
-
+use datafusion::catalog::Session;
+use datafusion::common::ScalarValue;
 use datafusion::config::ConfigOptions;
 use datafusion::datasource::MemTable;
 use datafusion::execution::runtime_env::{RuntimeConfig, RuntimeEnv};
@@ -39,14 +40,17 @@ impl PyBioSessionContext {
             ctx,
         })
     }
+    #[pyo3(signature = (key, value))]
+    pub fn set_option(&mut self, key: &str, value: &str) {
+        let mut state = self.ctx.state_ref();
+        state.write().config_mut().options_mut().set(key, value).unwrap();
+    }
 }
 
 
 fn create_context(algorithm: Algorithm) -> SessionContext {
     let mut options = ConfigOptions::new();
-    // FIXME
     let tuning_options = vec![
-        ("datafusion.execution.target_partitions", "1"),
         ("datafusion.optimizer.repartition_joins", "false"),
         ("datafusion.execution.coalesce_batches", "false"),
     ];
@@ -61,8 +65,7 @@ fn create_context(algorithm: Algorithm) -> SessionContext {
 
     let config = SessionConfig::from(options)
         .with_option_extension(sequila_config)
-        .with_information_schema(true)
-        .with_target_partitions(1);
+        .with_information_schema(true);
 
     SessionContext::new_with_sequila(config)
 }
@@ -119,6 +122,7 @@ fn overlap_frame(py_ctx: &PyBioSessionContext, df1: PyArrowType<ArrowArrayStream
 fn overlap_scan(py_ctx: &PyBioSessionContext, df_path1: String, df_path2: String) -> PyResult<PyDataFrame> {
     let rt = Runtime::new().unwrap();
     let ctx = &py_ctx.ctx;
+    println!("{}", ctx.state().config().options().execution.target_partitions);
     let s1_path = &df_path1;
     let s2_path = &df_path2;
     rt.block_on(register_parquet(&ctx, s1_path, "s1"));