Caching and state
Optimize performance and add statefulness to your app!
Caching
Streamlit provides powerful cache primitives for data and global resources. They allow your app to stay performant even when loading data from the web, manipulating large datasets, or performing expensive computations.
Cache data
Function decorator to cache functions that return data (e.g. dataframe transforms, database queries, ML inference).
@st.cache_data
def long_function(param1, param2):
# Perform expensive computation here or
# fetch data from the web here
return data
Cache resource
Function decorator to cache functions that return global resources (e.g. database connections, ML models).
@st.cache_resource
def init_model():
# Return a global resource here
return pipeline(
"sentiment-analysis",
model="distilbert-base-uncased-finetuned-sst-2-english"
)
Manage state
Streamlit re-executes your script with each user interaction. Widgets have built-in statefulness between reruns, but Session State lets you do more!
Session State
Save data between reruns and across pages.
st.session_state["foo"] = "bar"
Query parameters
Get, set, or clear the query parameters that are shown in the browser's URL bar.
st.query_params[key] = value
st.query_params.clear()
Deprecated commands
This command was deprecated in version 1.18.0. Use
st.cache_datainstead.
Memo
Experimental function decorator to memoize function executions.
@st.experimental_memo
def fetch_and_clean_data(url):
# Fetch data from URL here, and then clean it up.
return data
This command was deprecated in version 1.18.0. Use
st.cache_resourceinstead.
Singleton
Experimental function decorator to store singleton objects.
@st.experimental_singleton
def get_database_session(url):
# Create a database session object that points to the URL.
return session
Get query parameters
Get query parameters that are shown in the browser's URL bar.
param_dict = st.experimental_get_query_params()
Set query parameters
Set query parameters that are shown in the browser's URL bar.
st.experimental_set_query_params(
{"show_all"=True, "selected"=["asia", "america"]}
)
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